feat(angular.Module): add decorator method

Closes angular#11305
Closes angular#11300

Author: RodneyEbanks

src/loader.js

@@ -193,6 +193,18 @@ function setupModuleLoader(window) {
            */
           constant: invokeLater('$provide', 'constant', 'unshift'),
 
+           /**
+           * @ngdoc method
+           * @name angular.Module#decorator
+           * @module ng
+           * @param {string} The name of the service to decorate.
+           * @param {Function} This function will be invoked when the service needs to be
+           *                                    instantiated and should return the decorated service instance.
+           * @description
+           * See {@link auto.$provide#decorator $provide.decorator()}.
+           */
+          decorator: invokeLater('$provide', 'decorator'),
+
           /**
            * @ngdoc method
            * @name angular.Module#animation

test/loaderSpec.js

@@ -32,6 +32,7 @@ describe('module loader', function() {
     var myModule = window.angular.module('my', ['other'], 'config');
 
     expect(myModule.
+      decorator('dk', 'dv').
       provider('sk', 'sv').
       factory('fk', 'fv').
       service('a', 'aa').
@@ -46,6 +47,7 @@ describe('module loader', function() {
     expect(myModule.requires).toEqual(['other']);
     expect(myModule._invokeQueue).toEqual([
       ['$provide', 'constant', ['abc', 123]],
+      ['$provide', 'decorator', ['dk', 'dv']],
       ['$provide', 'provider', ['sk', 'sv']],
       ['$provide', 'factory', ['fk', 'fv']],
       ['$provide', 'service', ['a', 'aa']],