Bug 1363361 - Add ability to dirty root frame from nsIDOMWindowUtils.…

… r=dholbert

MozReview-Commit-ID: Jy6PICTkq4l

dom/base/nsDOMWindowUtils.cpp

@@ -4441,6 +4441,26 @@ nsDOMWindowUtils::GetDirectionFromText(const nsAString& aString, int32_t* aRetva
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsDOMWindowUtils::EnsureDirtyRootFrame()
+{
+  nsIDocument* doc = GetDocument();
+  nsIPresShell* presShell = doc ? doc->GetShell() : nullptr;
+
+  if (!presShell) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIFrame* frame = presShell->GetRootFrame();
+  if (!frame) {
+    return NS_ERROR_FAILURE;
+  }
+
+  presShell->FrameNeedsReflow(frame, nsIPresShell::eStyleChange,
+                              NS_FRAME_IS_DIRTY);
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsDOMWindowUtils::GetIsStyledByServo(bool* aStyledByServo)
 {

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -2023,6 +2023,14 @@ interface nsIDOMWindowUtils : nsISupports {
    */
   long getDirectionFromText(in AString aString);
 
+  /**
+   * Calls FrameNeedsReflow on that root frame so that a layout flush
+   * will be necessary.
+   *
+   * This should only be used for testing.
+   */
+  void ensureDirtyRootFrame();
+
   /**
    * Whether the current document is styled by Servo's style engine.
    *