fix($browser): remove base href domain when url begins with '//'

This change prevents an incorrect appBase url from being calculated when the
<base> href's domain begins with '//'.

Closes angular#5606

Author: caitp

src/ng/browser.js

@@ -253,7 +253,7 @@ function Browser(window, document, $log, $sniffer) {
    */
   self.baseHref = function() {
     var href = baseElement.attr('href');
-    return href ? href.replace(/^https?\:\/\/[^\/]*/, '') : '';
+    return href ? href.replace(/^(https?\:)?\/\/[^\/]*/, '') : '';
   };
 
   //////////////////////////////////////////////////////////////

test/ng/browserSpecs.js

@@ -609,5 +609,10 @@ describe('browser', function() {
       fakeDocument.basePath = 'http://host.com/base/path/index.html';
       expect(browser.baseHref()).toEqual('/base/path/index.html');
     });
+
+    it('should remove domain from <base href> beginning with \'//\'', function() {
+      fakeDocument.basePath = '//google.com/base/path/';
+      expect(browser.baseHref()).toEqual('/base/path/');
+    });
   });
 });