fix($parse): Make sure ES6 object computed property to be watched

Adding the missing watches for ES6 object property which added in angular#14407

Author: kindy

src/ng/parse.js

@@ -815,6 +815,13 @@ function findConstantAndWatchExpressions(ast, $filter) {
       if (!property.value.constant) {
         argsToWatch.push.apply(argsToWatch, property.value.toWatch);
       }
+      if (property.computed) {
+        findConstantAndWatchExpressions(property.key, $filter);
+        if (!property.key.constant) {
+          argsToWatch.push.apply(argsToWatch, property.key.toWatch);
+        }
+      }
+
     });
     ast.constant = allConstants;
     ast.toWatch = argsToWatch;

test/ng/parseSpec.js

@@ -3868,6 +3868,41 @@ describe('parser', function() {
           scope.$digest();
           expect(objB.value).toBe(scope.input);
         }));
+
+        it('should watch ES6 object computed property changes', function() {
+          var count = 0;
+          var values = [];
+          var firstValue = {'undefined': true};
+
+          scope.$watch('{[a]: true}', function(val, oldVal) {
+            count++;
+            values.push(val);
+          }, true);
+
+          scope.$digest();
+          expect(count).toBe(1);
+          expect(values[0]).toEqual(firstValue);
+
+          scope.$digest();
+          expect(count).toBe(1);
+          expect(values[0]).toEqual(firstValue);
+
+          scope.a = true;
+          scope.$digest();
+          expect(count).toBe(2);
+          expect(values[1]).toEqual({'true': true});
+
+          scope.a = 'abc';
+          scope.$digest();
+          expect(count).toBe(3);
+          expect(values[2]).toEqual({'abc': true});
+
+          scope.a = undefined;
+          scope.$digest();
+          expect(count).toBe(4);
+          expect(values[3]).toEqual({'undefined': true});
+        });
+
       });
 
       describe('locals', function() {