fix(core): fix decorator defalut values

modules/@angular/core/test/util/decorators_spec.ts

@@ -35,6 +35,18 @@ export function main() {
       const p = reflector.propMetadata(TestClass);
       expect(p['watch']).toEqual([new Prop('firefox!')]);
     });
+
+    it('should work with any default plain values', () => {
+      const Default = makePropDecorator('Default', [['value', 5]]);
+      expect(new Default(0)['value']).toEqual(0);
+    });
+
+    it('should work with any object values', () => {
+      // make sure we don't walk up the prototype chain
+      const Default = makePropDecorator('Default', [{value: 5}]);
+      const value = Object.create({value: 10});
+      expect(new Default(value)['value']).toEqual(5);
+    });
   });
 
   describe('decorators', () => {