docs(menu): fix broken link to spec (#11369)

Fixes #9959

Author: Splaktar

src/components/menu/demoMenuPositionModes/script.js

@@ -8,8 +8,6 @@ angular
   .controller('PositionDemoCtrl', function DemoCtrl($mdDialog) {
     var originatorEv;
 
-    this.menuHref = "http://www.google.com/design/spec/components/menus.html#menus-specs";
-
     this.openMenu = function($mdMenu, ev) {
       originatorEv = ev;
       $mdMenu.open(ev);

src/components/menu/demoMenuWidth/index.html

@@ -4,7 +4,7 @@
       <h2 class="md-title">Different Widths</h2>
       <p>
         <code>md-menu-content</code> may specify a <code>width</code> attribute which will follow
-        the <a href="ctrl.menuHref" class="md-accent">official spec</a>.
+        the <a ng-href="{{ctrl.menuHref}}" class="md-accent" target="_blank">official spec</a>.
       </p>
     </div>
     <div class="menus" layout-wrap layout="row" layout-fill layout-align="space-between center" style="min-height:100px;">

src/components/menu/demoMenuWidth/script.js

@@ -3,7 +3,8 @@ angular.module('menuDemoWidth', ['ngMaterial']).config(function($mdIconProvider)
     .iconSet("call", 'img/icons/sets/communication-icons.svg', 24)
     .iconSet("social", 'img/icons/sets/social-icons.svg', 24);
 }).controller('WidthDemoCtrl', function($mdDialog) {
-  var vm = this;
+  var ctrl = this;
+  ctrl.menuHref = "https://material.io/design/components/menus.html#specs";
 
   this.announceClick = function(index) {
     $mdDialog.show(