fix($injector): fix class detection RegExp

Mentioned in https://github.com/angular/angular.js/pull/14531#discussion_r61410683.

Closes #14533

src/auto/injector.js

@@ -855,9 +855,9 @@ function createInjector(modulesToLoad, strictDi) {
       }
       var result = func.$$ngIsClass;
       if (!isBoolean(result)) {
-        // Workaround for MS Edge.
-        // Check https://connect.microsoft.com/IE/Feedback/Details/2211653
-        result = func.$$ngIsClass = /^(?:class\s|constructor\()/.test(stringifyFn(func));
+        // Support: Edge 12-13 only
+        // See: https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/6156135/
+        result = func.$$ngIsClass = /^(?:class\b|constructor\()/.test(stringifyFn(func));
       }
       return result;
     }

test/auto/injectorSpec.js

@@ -302,6 +302,26 @@ describe('injector', function() {
           expect(instance.aVal()).toEqual('a-value');
         });
 
+        if (/chrome/.test(navigator.userAgent)) {
+          they('should detect ES6 classes regardless of whitespace/comments ($prop)', [
+            'class Test {}',
+            'class Test{}',
+            'class //<--ES6 stuff\nTest {}',
+            'class//<--ES6 stuff\nTest {}',
+            'class {}',
+            'class{}',
+            'class //<--ES6 stuff\n {}',
+            'class//<--ES6 stuff\n {}',
+            'class/* Test */{}',
+            'class /* Test */ {}'
+          ], function(classDefinition) {
+            var Clazz = eval('(' + classDefinition + ')');
+            var instance = injector.invoke(Clazz);
+
+            expect(instance).toEqual(jasmine.any(Clazz));
+          });
+        }
+
         // Support: Chrome 50-51 only
         // TODO (gkalpak): Remove when Chrome v52 is relased.
         // it('should be able to invoke classes', function() {