fix($compile): do not use noop() as controller for multiple components

Currently, custom annotations are copied from the CDO onto the controller constructor.
Using `noop()` when no controller has been specified, pollutes it with custom annotations and
makes one component's annotations available to all other components that have `noop()` as their
controller.

Fixes #14391
Closes #14402

Author: gkalpak

src/ng/compile.js

@@ -1092,7 +1092,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
    * See also {@link ng.$compileProvider#directive $compileProvider.directive()}.
    */
   this.component = function registerComponent(name, options) {
-    var controller = options.controller || noop;
+    var controller = options.controller || function() {};
 
     function factory($injector) {
       function makeInjectable(fn) {

test/ng/compileSpec.js

@@ -10506,7 +10506,7 @@ describe('$compile', function() {
     });
 
     it('should expose additional annotations on the directive definition object', function() {
-      var myModule = angular.module('my', []).component('myComponent', {
+      angular.module('my', []).component('myComponent', {
         $canActivate: 'canActivate',
         $routeConfig: 'routeConfig',
         $customAnnotation: 'XXX'
@@ -10522,7 +10522,7 @@ describe('$compile', function() {
     });
 
     it('should support custom annotations if the controller is named', function() {
-      var myModule = angular.module('my', []).component('myComponent', {
+      angular.module('my', []).component('myComponent', {
         $customAnnotation: 'XXX',
         controller: 'SomeNamedController'
       });
@@ -10534,6 +10534,26 @@ describe('$compile', function() {
       });
     });
 
+    it('should provide a new empty controller if none is specified', function() {
+      angular.
+        module('my', []).
+        component('myComponent1', {$customAnnotation1: 'XXX'}).
+        component('myComponent2', {$customAnnotation2: 'YYY'});
+
+      module('my');
+
+      inject(function(myComponent1Directive, myComponent2Directive) {
+        var ctrl1 = myComponent1Directive[0].controller;
+        var ctrl2 = myComponent2Directive[0].controller;
+
+        expect(ctrl1).not.toBe(ctrl2);
+        expect(ctrl1.$customAnnotation1).toBe('XXX');
+        expect(ctrl1.$customAnnotation2).toBeUndefined();
+        expect(ctrl2.$customAnnotation1).toBeUndefined();
+        expect(ctrl2.$customAnnotation2).toBe('YYY');
+      });
+    });
+
     it('should return ddo with reasonable defaults', function() {
       angular.module('my', []).component('myComponent', {});
       module('my');