fix(ng-bind-html): watch string value instead of wrapper

src/ng/directive/ngBind.js

@@ -134,11 +134,15 @@ var ngBindTemplateDirective = ['$interpolate', function($interpolate) {
  * @element ANY
  * @param {expression} ngBindHtml {@link guide/expression Expression} to evaluate.
  */
-var ngBindHtmlDirective = ['$sce', function($sce) {
+var ngBindHtmlDirective = ['$sce', '$parse', function($sce, $parse) {
   return function(scope, element, attr) {
     element.addClass('ng-binding').data('$binding', attr.ngBindHtml);
-    scope.$watch(attr.ngBindHtml, function ngBindHtmlWatchAction(value) {
-      element.html($sce.getTrustedHtml(value) || '');
+
+    var parsed = $parse(attr.ngBindHtml);
+    function getStringValue() { return (parsed(scope) || '').toString(); }
+
+    scope.$watch(getStringValue, function ngBindHtmlWatchAction(value) {
+      element.html($sce.getTrustedHtml(parsed(scope)) || '');
     });
   };
 }];

test/ng/directive/ngBindSpec.js

@@ -102,6 +102,18 @@ describe('ngBind*', function() {
         expect(angular.lowercase(element.html())).toEqual('<div onclick="">hello</div>');
       }));
 
+      it('should watch the string value to avoid infinite recursion', inject(function($rootScope, $compile, $sce) {
+        // Ref: https://github.com/angular/angular.js/issues/3932
+        // If the binding is a function that creates a new value on every call via trustAs, we'll
+        // trigger an infinite digest if we don't take care of it.
+        element = $compile('<div ng-bind-html="getHtml()"></div>')($rootScope);
+        $rootScope.getHtml = function() {
+          return $sce.trustAsHtml('<div onclick="">hello</div>');
+        };
+        $rootScope.$digest();
+        expect(angular.lowercase(element.html())).toEqual('<div onclick="">hello</div>');
+      }));
+
       describe('when $sanitize is available', function() {
         beforeEach(function() { module('ngSanitize'); });