fix(input): update $viewValue when cleared

- Fix when user clicks clear button in an input element in IE, $viewValue not being correctly updated

Author: wesleycho

src/ng/directive/input.js

@@ -1127,6 +1127,7 @@ function baseInputType(scope, element, attr, ctrl, $sniffer, $browser) {
   }
 
   var timeout;
+  var oldVal = element.val();
 
   var listener = function(ev) {
     if (timeout) {
@@ -1152,10 +1153,17 @@ function baseInputType(scope, element, attr, ctrl, $sniffer, $browser) {
     }
   };
 
+  function ieListener(ev) {
+    var val = element.val();
+    if (val === oldVal) return;
+    oldVal = val;
+    listener(ev);
+  }
+
   // if the browser does support "input" event, we are fine - except on IE9 which doesn't fire the
   // input event on backspace, delete or cut
   if ($sniffer.hasEvent('input')) {
-    element.on('input', listener);
+    element.on('input', msie ? ieListener : listener);
   } else {
     var deferListener = function(ev, input, origValue) {
       if (!timeout) {

src/ng/sniffer.js

@@ -73,7 +73,7 @@ function $SnifferProvider() {
         // when cut operation is performed.
         // IE10+ implements 'input' event but it erroneously fires under various situations,
         // e.g. when placeholder changes, or a form is focused.
-        if (event === 'input' && msie <= 11) return false;
+        if (event === 'input' && msie <= 9) return false;
 
         if (isUndefined(eventSupport[event])) {
           var divElm = document.createElement('div');

test/ng/snifferSpec.js

@@ -135,7 +135,7 @@ describe('$sniffer', function() {
       // IE10+ implementation is fubared when mixed with placeholders
       mockDivElement = {oninput: noop};
 
-      expect($sniffer.hasEvent('input')).toBe(!(msie && msie <= 11));
+      expect($sniffer.hasEvent('input')).toBe(!(msie && msie <= 9));
     });
   });