fix(ngBind): use same json conversion as $interpolate

Fixes #11716

BREAKING CHANGE:

`ngBind` now uses the same logic as $interpolate (i.e. {{myString}}) when
binding, which means objects are now transformed with JSON.stringify. Before, it
would use the object's toString() function.

The following example shows the different output:
```js
$scope.myObject = {a: 1, b: 2};
```

```html
<span ng-bind="myObject"></span>
```

Before:
```html
<span ng-bind="myObject">[object Object]</span>
```

After:
```html
<span ng-bind="myObject">{"a":1,"b":2}</span>
```

Author: Narretz

src/.jshintrc

@@ -96,6 +96,7 @@
     "createMap": false,
     "VALIDITY_STATE_PROPERTY": false,
     "reloadWithDebugInfo": false,
+    "stringify": false,
 
     "NODE_TYPE_ELEMENT": false,
     "NODE_TYPE_ATTRIBUTE": false,

src/Angular.js

@@ -87,6 +87,7 @@
   getBlockNodes: true,
   hasOwnProperty: true,
   createMap: true,
+  stringify: true,
 
   NODE_TYPE_ELEMENT: true,
   NODE_TYPE_ATTRIBUTE: true,
@@ -1929,6 +1930,24 @@ function createMap() {
   return Object.create(null);
 }
 
+
+function stringify(value) {
+  if (value == null) { // null || undefined
+    return '';
+  }
+  switch (typeof value) {
+    case 'string':
+      break;
+    case 'number':
+      value = '' + value;
+      break;
+    default:
+      value = toJson(value);
+  }
+
+  return value;
+}
+
 var NODE_TYPE_ELEMENT = 1;
 var NODE_TYPE_ATTRIBUTE = 2;
 var NODE_TYPE_TEXT = 3;

src/ng/directive/ngBind.js

@@ -60,7 +60,7 @@ var ngBindDirective = ['$compile', function($compile) {
         $compile.$$addBindingInfo(element, attr.ngBind);
         element = element[0];
         scope.$watch(attr.ngBind, function ngBindWatchAction(value) {
-          element.textContent = isUndefined(value) ? '' : value;
+          element.textContent = isUndefined(value) ? '' : stringify(value);
         });
       };
     }

src/ng/interpolate.js

@@ -111,23 +111,6 @@ function $InterpolateProvider() {
         replace(escapedEndRegexp, endSymbol);
     }
 
-    function stringify(value) {
-      if (value == null) { // null || undefined
-        return '';
-      }
-      switch (typeof value) {
-        case 'string':
-          break;
-        case 'number':
-          value = '' + value;
-          break;
-        default:
-          value = toJson(value);
-      }
-
-      return value;
-    }
-
     //TODO: this is the same as the constantWatchDelegate in parse.js
     function constantWatchDelegate(scope, listener, objectEquality, constantInterp) {
       var unwatch;

test/ng/directive/ngBindSpec.js

@@ -46,6 +46,15 @@ describe('ngBind*', function() {
       expect(element.text()).toEqual('-0false');
     }));
 
+    they('should jsonify $prop', [[{a: 1}, '{"a":1}'], [true, 'true'], [false, 'false']], function(prop) {
+      inject(function($rootScope, $compile) {
+        $rootScope.bind = prop[0];
+        element = $compile('<div ng-bind="bind"></div>')($rootScope);
+        $rootScope.$digest();
+        expect(element.text()).toEqual(prop[1]);
+      });
+    });
+
     it('should one-time bind if the expression starts with two colons', inject(function($rootScope, $compile) {
       element = $compile('<div ng-bind="::a"></div>')($rootScope);
       $rootScope.a = 'lucas';