docs: fix remaining broken links (#2832)

* docs: fix remaining broken links In particular, don’t show the language dropdown for the docs change-log page (since JS and Dart don’t have a change log). Together with #2830, this fixes #2150

* ignore invalid link from about bios

gulpfile.js

@@ -793,7 +793,9 @@ gulp.task('link-checker', function(done) {
     'resources/%7B%7Bresource.url%7D%7D',
     // API docs have links directly into GitHub repo sources; these can
     // quickly become invalid, so ignore them for now:
-    '*/angular/tree/*'
+    '*/angular/tree/*',
+    // harp.json "bios" for "Ryan Schmukler", URL isn't valid:
+    'http://slingingcode.com'
   ];
   var blcOptions = { requestMethod: method, excludedKeywords: exclude};
   return linkChecker({ blcOptions: blcOptions });

public/_includes/_version-dropdown.jade

@@ -61,13 +61,13 @@ if language == 'dart'
   else
     - var title = 'Angular ' + version + ' for Dart'
 
-
-<!-- DROPDOWN BUTTON -->
-nav.dropdown
+if current.path[4] !== 'change-log'
+  //- DROPDOWN BUTTON
+  nav.dropdown
     button(aria-label="Select a version of Angular" md-button class="dropdown-button" ng-click="appCtrl.toggleVersionMenu($event)") #{title}  <span class="icon icon-arrow-drop-down"></span>
     div(class="overlay ng-hide" ng-click="appCtrl.toggleVersionMenu($event)" ng-show="appCtrl.showMenu")
 
-  <!-- DROPDOWN MENU -->
+    //- DROPDOWN MENU
     ul(class="dropdown-menu" ng-class="appCtrl.showMenu ? 'is-visible' : ''")
       mixin tree(public.docs.ts, "/docs/ts", "Angular for TypeScript")
       mixin tree(public.docs.js, "/docs/js", "Angular for JavaScript")

public/docs/js/latest/quickstart.jade

@@ -282,7 +282,7 @@ code-example(format="").
 
   Create a `styles.css` file in the *#{_indexHtmlDir}* folder and start styling, perhaps with the minimal
   styles shown below. For the full set of master styles used by the documentation samples,
-  see [styles.css](https://github.com/angular/angular.io/blob/master/public/docs/_examples/styles.css).
+  see [styles.css](https://github.com/angular/angular.io/blob/master/public/docs/_examples/_boilerplate/styles.css).
 +makeExample('quickstart/js/styles.1.css', null, 'styles.css')(format=".")
 
 .l-main-section