Avoid WTF::Vector::at() and operator[] in core/html.

at() and operator[] are slow due to RELEASE_ASSERT. We can avoid the slowness by
range-based |for|.

This CL has no behavior changes except runtime performance.

BUG=668300

Review-Url: https://codereview.chromium.org/2556043002
Cr-Commit-Position: refs/heads/master@{#437175}

third_party/WebKit/Source/core/html/HTMLCollection.cpp

@@ -512,13 +512,13 @@ void HTMLCollection::namedItems(const AtomicString& name,
 
   const NamedItemCache& cache = namedItemCache();
   if (HeapVector<Member<Element>>* idResults = cache.getElementsById(name)) {
-    for (unsigned i = 0; i < idResults->size(); ++i)
-      result.append(idResults->at(i));
+    for (const auto& element : *idResults)
+      result.append(element);
   }
   if (HeapVector<Member<Element>>* nameResults =
           cache.getElementsByName(name)) {
-    for (unsigned i = 0; i < nameResults->size(); ++i)
-      result.append(nameResults->at(i));
+    for (const auto& element : *nameResults)
+      result.append(element);
   }
 }
 

third_party/WebKit/Source/core/html/HTMLElement.cpp

@@ -419,9 +419,8 @@ const AtomicString& HTMLElement::eventNameForAttributeName(
         {onwheelAttr, EventTypeNames::wheel},
     };
 
-    for (size_t i = 0; i < WTF_ARRAY_LENGTH(attrToEventNames); i++)
-      attributeNameToEventNameMap.set(attrToEventNames[i].attr.localName(),
-                                      attrToEventNames[i].event);
+    for (const auto& name : attrToEventNames)
+      attributeNameToEventNameMap.set(name.attr.localName(), name.event);
   }
 
   return attributeNameToEventNameMap.get(attrName.localName());

third_party/WebKit/Source/core/html/HTMLFormControlsCollection.cpp

@@ -108,9 +108,9 @@ static HTMLElement* firstNamedItem(const ListedElement::List& elementsArray,
                                    const String& name) {
   DCHECK(attrName == idAttr || attrName == nameAttr);
 
-  for (unsigned i = 0; i < elementsArray.size(); ++i) {
-    HTMLElement* element = toHTMLElement(elementsArray[i]);
-    if (elementsArray[i]->isEnumeratable() &&
+  for (const auto& listedElement : elementsArray) {
+    HTMLElement* element = toHTMLElement(listedElement);
+    if (listedElement->isEnumeratable() &&
         element->fastGetAttribute(attrName) == name)
       return element;
   }
@@ -136,10 +136,7 @@ void HTMLFormControlsCollection::updateIdNameCache() const {
   NamedItemCache* cache = NamedItemCache::create();
   HashSet<StringImpl*> foundInputElements;
 
-  const ListedElement::List& elementsArray = listedElements();
-
-  for (unsigned i = 0; i < elementsArray.size(); ++i) {
-    ListedElement* listedElement = elementsArray[i];
+  for (const auto& listedElement : listedElements()) {
     if (listedElement->isEnumeratable()) {
       HTMLElement* element = toHTMLElement(listedElement);
       const AtomicString& idAttrVal = element->getIdAttribute();
@@ -158,10 +155,7 @@ void HTMLFormControlsCollection::updateIdNameCache() const {
   // HTMLFormControlsCollection doesn't support named getter for IMG
   // elements. However we still need to handle IMG elements here because
   // HTMLFormElement named getter relies on this.
-  const HeapVector<Member<HTMLImageElement>>& imageElementsArray =
-      formImageElements();
-  for (unsigned i = 0; i < imageElementsArray.size(); ++i) {
-    HTMLImageElement* element = imageElementsArray[i];
+  for (const auto& element : formImageElements()) {
     const AtomicString& idAttrVal = element->getIdAttribute();
     const AtomicString& nameAttrVal = element->getNameAttribute();
     if (!idAttrVal.isEmpty() && !foundInputElements.contains(idAttrVal.impl()))

third_party/WebKit/Source/core/html/HTMLFormElement.cpp

@@ -194,10 +194,9 @@ void HTMLFormElement::handleLocalEvents(Event& event) {
 }
 
 unsigned HTMLFormElement::length() const {
-  const ListedElement::List& elements = listedElements();
   unsigned len = 0;
-  for (unsigned i = 0; i < elements.size(); ++i) {
-    if (elements[i]->isEnumeratable())
+  for (const auto& element : listedElements()) {
+    if (element->isEnumeratable())
       ++len;
   }
   return len;
@@ -211,12 +210,10 @@ void HTMLFormElement::submitImplicitly(Event* event,
                                        bool fromImplicitSubmissionTrigger) {
   int submissionTriggerCount = 0;
   bool seenDefaultButton = false;
-  const ListedElement::List& elements = listedElements();
-  for (unsigned i = 0; i < elements.size(); ++i) {
-    ListedElement* ListedElement = elements[i];
-    if (!ListedElement->isFormControlElement())
+  for (const auto& element : listedElements()) {
+    if (!element->isFormControlElement())
       continue;
-    HTMLFormControlElement* control = toHTMLFormControlElement(ListedElement);
+    HTMLFormControlElement* control = toHTMLFormControlElement(element);
     if (!seenDefaultButton && control->canBeSuccessfulSubmitButton()) {
       if (fromImplicitSubmissionTrigger)
         seenDefaultButton = true;
@@ -238,10 +235,9 @@ void HTMLFormElement::submitImplicitly(Event* event,
 
 bool HTMLFormElement::validateInteractively() {
   UseCounter::count(document(), UseCounter::FormValidationStarted);
-  const ListedElement::List& elements = listedElements();
-  for (unsigned i = 0; i < elements.size(); ++i) {
-    if (elements[i]->isFormControlElement())
-      toHTMLFormControlElement(elements[i])->hideVisibleValidationMessage();
+  for (const auto& element : listedElements()) {
+    if (element->isFormControlElement())
+      toHTMLFormControlElement(element)->hideVisibleValidationMessage();
   }
 
   HeapVector<Member<HTMLFormControlElement>> unhandledInvalidControls;
@@ -257,8 +253,7 @@ bool HTMLFormElement::validateInteractively() {
   document().updateStyleAndLayoutIgnorePendingStylesheets();
 
   // Focus on the first focusable control and show a validation message.
-  for (unsigned i = 0; i < unhandledInvalidControls.size(); ++i) {
-    HTMLFormControlElement* unhandled = unhandledInvalidControls[i].get();
+  for (const auto& unhandled : unhandledInvalidControls) {
     if (unhandled->isFocusable()) {
       unhandled->showValidationMessage();
       UseCounter::count(document(), UseCounter::FormValidationShowedMessage);
@@ -267,8 +262,7 @@ bool HTMLFormElement::validateInteractively() {
   }
   // Warn about all of unfocusable controls.
   if (document().frame()) {
-    for (unsigned i = 0; i < unhandledInvalidControls.size(); ++i) {
-      HTMLFormControlElement* unhandled = unhandledInvalidControls[i].get();
+    for (const auto& unhandled : unhandledInvalidControls) {
       if (unhandled->isFocusable())
         continue;
       String message(
@@ -471,10 +465,9 @@ void HTMLFormElement::reset() {
     return;
   }
 
-  const ListedElement::List& elements = listedElements();
-  for (unsigned i = 0; i < elements.size(); ++i) {
-    if (elements[i]->isFormControlElement())
-      toHTMLFormControlElement(elements[i])->reset();
+  for (const auto& element : listedElements()) {
+    if (element->isFormControlElement())
+      toHTMLFormControlElement(element)->reset();
   }
 
   m_isInResetFunction = false;
@@ -664,13 +657,12 @@ bool HTMLFormElement::checkInvalidControlsAndCollectUnhandled(
   const ListedElement::List& listedElements = this->listedElements();
   HeapVector<Member<ListedElement>> elements;
   elements.reserveCapacity(listedElements.size());
-  for (unsigned i = 0; i < listedElements.size(); ++i)
-    elements.append(listedElements[i]);
+  for (const auto& element : listedElements)
+    elements.append(element);
   int invalidControlsCount = 0;
-  for (unsigned i = 0; i < elements.size(); ++i) {
-    if (elements[i]->form() == this && elements[i]->isFormControlElement()) {
-      HTMLFormControlElement* control =
-          toHTMLFormControlElement(elements[i].get());
+  for (const auto& element : elements) {
+    if (element->form() == this && element->isFormControlElement()) {
+      HTMLFormControlElement* control = toHTMLFormControlElement(element);
       if (control->isSubmittableElement() &&
           !control->checkValidity(unhandledInvalidControls, eventBehavior) &&
           control->formOwner() == this) {

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

@@ -1230,11 +1230,9 @@ bool HTMLMediaElement::textTracksAreReady() const {
   // mode was not in the disabled state when the element's resource selection
   // algorithm last started now have a text track readiness state of loaded or
   // failed to load.
-  for (unsigned i = 0; i < m_textTracksWhenResourceSelectionBegan.size(); ++i) {
-    if (m_textTracksWhenResourceSelectionBegan[i]->getReadinessState() ==
-            TextTrack::Loading ||
-        m_textTracksWhenResourceSelectionBegan[i]->getReadinessState() ==
-            TextTrack::NotLoaded)
+  for (const auto& textTrack : m_textTracksWhenResourceSelectionBegan) {
+    if (textTrack->getReadinessState() == TextTrack::Loading ||
+        textTrack->getReadinessState() == TextTrack::NotLoaded)
       return false;
   }
 

third_party/WebKit/Source/core/html/HTMLTextAreaElement.cpp

@@ -480,9 +480,8 @@ void HTMLTextAreaElement::setDefaultValue(const String& defaultValue) {
     if (n->isTextNode())
       textNodes.append(n);
   }
-  size_t size = textNodes.size();
-  for (size_t i = 0; i < size; ++i)
-    removeChild(textNodes[i].get(), IGNORE_EXCEPTION);
+  for (const auto& text : textNodes)
+    removeChild(text.get(), IGNORE_EXCEPTION);
 
   // Normalize line endings.
   String value = defaultValue;

third_party/WebKit/Source/core/html/MediaFragmentURIParser.cpp

@@ -150,9 +150,7 @@ void MediaFragmentURIParser::parseTimeFragment() {
 
   m_timeFormat = Invalid;
 
-  for (unsigned i = 0; i < m_fragments.size(); ++i) {
-    std::pair<String, String>& fragment = m_fragments[i];
-
+  for (const auto& fragment : m_fragments) {
     DCHECK(fragment.first.is8Bit());
     DCHECK(fragment.second.is8Bit());
 

third_party/WebKit/Source/core/html/PublicURLManager.cpp

@@ -87,8 +87,8 @@ void PublicURLManager::revoke(const String& uuid) {
         urlsToRemove.append(registeredUrl.key);
       }
     }
-    for (unsigned j = 0; j < urlsToRemove.size(); j++)
-      registeredURLs.remove(urlsToRemove[j]);
+    for (const auto& url : urlsToRemove)
+      registeredURLs.remove(url);
     urlsToRemove.clear();
   }
 }

third_party/WebKit/Source/core/html/forms/EmailInputType.cpp

@@ -186,8 +186,8 @@ String EmailInputType::findInvalidAddress(const String& value) const {
     return isValidEmailAddress(ensureEmailRegexp(), value) ? String() : value;
   Vector<String> addresses;
   value.split(',', true, addresses);
-  for (unsigned i = 0; i < addresses.size(); ++i) {
-    String stripped = stripLeadingAndTrailingHTMLSpaces(addresses[i]);
+  for (const auto& address : addresses) {
+    String stripped = stripLeadingAndTrailingHTMLSpaces(address);
     if (!isValidEmailAddress(ensureEmailRegexp(), stripped))
       return stripped;
   }

third_party/WebKit/Source/core/html/forms/FileInputType.cpp

@@ -225,24 +225,22 @@ FileList* FileInputType::createFileList(
     int rootLength = rootPath.length();
     if (rootPath[rootLength - 1] != '\\' && rootPath[rootLength - 1] != '/')
       rootLength += 1;
-    for (size_t i = 0; i < size; ++i) {
+    for (const auto& file : files) {
       // Normalize backslashes to slashes before exposing the relative path to
       // script.
-      String relativePath =
-          files[i].path.substring(rootLength).replace('\\', '/');
-      fileList->append(
-          File::createWithRelativePath(files[i].path, relativePath));
+      String relativePath = file.path.substring(rootLength).replace('\\', '/');
+      fileList->append(File::createWithRelativePath(file.path, relativePath));
     }
     return fileList;
   }
 
-  for (size_t i = 0; i < size; ++i) {
-    if (files[i].fileSystemURL.isEmpty()) {
+  for (const auto& file : files) {
+    if (file.fileSystemURL.isEmpty()) {
       fileList->append(
-          File::createForUserProvidedFile(files[i].path, files[i].displayName));
+          File::createForUserProvidedFile(file.path, file.displayName));
     } else {
       fileList->append(File::createForFileSystemFile(
-          files[i].fileSystemURL, files[i].metadata, File::IsUserVisible));
+          file.fileSystemURL, file.metadata, File::IsUserVisible));
     }
   }
   return fileList;
@@ -352,8 +350,8 @@ void FileInputType::setFilesFromPaths(const Vector<String>& paths) {
   }
 
   Vector<FileChooserFileInfo> files;
-  for (unsigned i = 0; i < paths.size(); ++i)
-    files.append(FileChooserFileInfo(paths[i]));
+  for (const auto& path : paths)
+    files.append(FileChooserFileInfo(path));
 
   if (input.fastHasAttribute(multipleAttr)) {
     filesChosen(files);

third_party/WebKit/Source/core/html/forms/FormController.cpp

@@ -60,8 +60,8 @@ static inline HTMLFormElement* ownerFormForState(
 void FormControlState::serializeTo(Vector<String>& stateVector) const {
   DCHECK(!isFailure());
   stateVector.append(String::number(m_values.size()));
-  for (size_t i = 0; i < m_values.size(); ++i)
-    stateVector.append(m_values[i].isNull() ? emptyString() : m_values[i]);
+  for (const auto& value : m_values)
+    stateVector.append(value.isNull() ? emptyString() : value);
 }
 
 FormControlState FormControlState::deserialize(
@@ -295,8 +295,8 @@ Vector<String> SavedFormState::getReferencedFilePaths() const {
       const Vector<FileChooserFileInfo>& selectedFiles =
           HTMLInputElement::filesFromFileInputFormControlState(
               formControlState);
-      for (size_t i = 0; i < selectedFiles.size(); ++i)
-        toReturn.append(selectedFiles[i].path);
+      for (const auto& file : selectedFiles)
+        toReturn.append(file.path);
     }
   }
   return toReturn;

third_party/WebKit/Source/core/html/imports/HTMLImport.cpp

@@ -106,8 +106,8 @@ void HTMLImport::recalcTreeState(HTMLImport* root) {
       updated.append(i);
   }
 
-  for (size_t i = 0; i < updated.size(); ++i)
-    updated[i]->stateDidChange();
+  for (const auto& import : updated)
+    import->stateDidChange();
 }
 
 #if !defined(NDEBUG)

third_party/WebKit/Source/core/html/imports/HTMLImportLoader.cpp

@@ -171,8 +171,8 @@ bool HTMLImportLoader::hasPendingResources() const {
 }
 
 void HTMLImportLoader::didFinishLoading() {
-  for (size_t i = 0; i < m_imports.size(); ++i)
-    m_imports[i]->didFinishLoading();
+  for (const auto& importChild : m_imports)
+    importChild->didFinishLoading();
 
   clearResource();
 

third_party/WebKit/Source/core/html/imports/HTMLImportTreeRoot.cpp

@@ -25,8 +25,8 @@ HTMLImportTreeRoot::HTMLImportTreeRoot(Document* document)
 HTMLImportTreeRoot::~HTMLImportTreeRoot() {}
 
 void HTMLImportTreeRoot::dispose() {
-  for (size_t i = 0; i < m_imports.size(); ++i)
-    m_imports[i]->dispose();
+  for (const auto& importChild : m_imports)
+    importChild->dispose();
   m_imports.clear();
   m_document = nullptr;
   m_recalcTimer.stop();
@@ -67,8 +67,7 @@ HTMLImportChild* HTMLImportTreeRoot::add(HTMLImportChild* child) {
 }
 
 HTMLImportChild* HTMLImportTreeRoot::find(const KURL& url) const {
-  for (size_t i = 0; i < m_imports.size(); ++i) {
-    HTMLImportChild* candidate = m_imports[i].get();
+  for (const auto& candidate : m_imports) {
     if (equalIgnoringFragmentIdentifier(candidate->url(), url))
       return candidate;
   }

third_party/WebKit/Source/core/html/imports/HTMLImportsController.cpp

@@ -52,8 +52,8 @@ void HTMLImportsController::dispose() {
     m_root.clear();
   }
 
-  for (size_t i = 0; i < m_loaders.size(); ++i)
-    m_loaders[i]->dispose();
+  for (const auto& loader : m_loaders)
+    loader->dispose();
   m_loaders.clear();
 }
 
@@ -139,9 +139,9 @@ HTMLImportLoader* HTMLImportsController::createLoader() {
 
 HTMLImportLoader* HTMLImportsController::loaderFor(
     const Document& document) const {
-  for (size_t i = 0; i < m_loaders.size(); ++i) {
-    if (m_loaders[i]->document() == &document)
-      return m_loaders[i].get();
+  for (const auto& loader : m_loaders) {
+    if (loader->document() == &document)
+      return loader.get();
   }
 
   return nullptr;

third_party/WebKit/Source/core/html/parser/AtomicHTMLToken.h

@@ -222,8 +222,7 @@ inline void AtomicHTMLToken::initializeAttributes(
 
   m_attributes.clear();
   m_attributes.reserveInitialCapacity(size);
-  for (size_t i = 0; i < size; ++i) {
-    const HTMLToken::Attribute& attribute = attributes[i];
+  for (const auto& attribute : attributes) {
     if (attribute.nameAsVector().isEmpty())
       continue;
 

third_party/WebKit/Source/core/html/parser/BackgroundHTMLInputStream.cpp

@@ -115,10 +115,10 @@ void BackgroundHTMLInputStream::rewindTo(HTMLInputCheckpoint checkpointIndex,
 
 void BackgroundHTMLInputStream::updateTotalCheckpointTokenCount() {
   m_totalCheckpointTokenCount = 0;
-  size_t lastCheckpointIndex = m_checkpoints.size();
-  for (size_t i = 0; i < lastCheckpointIndex; ++i)
+  for (const auto& checkpoint : m_checkpoints) {
     m_totalCheckpointTokenCount +=
-        m_checkpoints[i].tokensExtractedSincePreviousCheckpoint;
+        checkpoint.tokensExtractedSincePreviousCheckpoint;
+  }
 }
 
 }  // namespace blink

third_party/WebKit/Source/core/html/parser/HTMLConstructionSite.cpp

@@ -321,8 +321,8 @@ void HTMLConstructionSite::executeQueuedTasks() {
   TaskQueue queue;
   queue.swap(m_taskQueue);
 
-  for (size_t i = 0; i < size; ++i)
-    executeTask(queue[i]);
+  for (auto& task : queue)
+    executeTask(task);
 
   // We might be detached now.
 }
@@ -407,8 +407,7 @@ void HTMLConstructionSite::mergeAttributesFromTokenIntoElement(
   if (token->attributes().isEmpty())
     return;
 
-  for (unsigned i = 0; i < token->attributes().size(); ++i) {
-    const Attribute& tokenAttribute = token->attributes().at(i);
+  for (const auto& tokenAttribute : token->attributes()) {
     if (element->attributesWithoutUpdate().findIndex(tokenAttribute.name()) ==
         kNotFound)
       element->setAttribute(tokenAttribute.name(), tokenAttribute.value());