docs(ngModelController): use $sce and $sanitize in the contenteditable example.

Closes #7464

src/ng/directive/input.js

@@ -934,7 +934,12 @@ var VALID_CLASS = 'ng-valid',
  * Note that `contenteditable` is an HTML5 attribute, which tells the browser to let the element
  * contents be edited in place by the user.  This will not work on older browsers.
  *
- * <example name="NgModelController" module="customControl">
+ * We are using the {@link ng.service:$sce $sce} service here and include the {@link ngSanitize $sanitize}
+ * module to automatically remove "bad" content like inline event listener (e.g. `<span onclick="...">`).
+ * However, as we are using `$sce` the model can still decide to to provide unsafe content if it marks
+ * that content using the `$sce` service.
+ *
+ * <example name="NgModelController" module="customControl" deps="angular-sanitize.js">
     <file name="style.css">
       [contenteditable] {
         border: 1px solid black;
@@ -948,8 +953,8 @@ var VALID_CLASS = 'ng-valid',
 
     </file>
     <file name="script.js">
-      angular.module('customControl', []).
-        directive('contenteditable', function() {
+      angular.module('customControl', ['ngSanitize']).
+        directive('contenteditable', ['$sce', function($sce) {
           return {
             restrict: 'A', // only activate on element attribute
             require: '?ngModel', // get a hold of NgModelController
@@ -958,7 +963,7 @@ var VALID_CLASS = 'ng-valid',
 
               // Specify how UI should be updated
               ngModel.$render = function() {
-                element.html(ngModel.$viewValue || '');
+                element.html($sce.getTrustedHtml(ngModel.$viewValue || ''));
               };
 
               // Listen for change events to enable binding
@@ -979,7 +984,7 @@ var VALID_CLASS = 'ng-valid',
               }
             }
           };
-        });
+        }]);
     </file>
     <file name="index.html">
       <form name="myForm">