fix($location): throw if the path starts with double (back)slashes

Previously `$location` was rewriting such paths to remove not only the
double slashes but also the first segment of the path, leading to an invalid
path.

In this change, we deem leading double (back)slashes an invalid path and
now throw a `$location:badpath` error if that occurs.

Author: petebacondarwin

src/ng/location.js

@@ -30,10 +30,10 @@ function parseAbsoluteUrl(absoluteUrl, locationObj) {
   locationObj.$$port = toInt(parsedUrl.port) || DEFAULT_PORTS[parsedUrl.protocol] || null;
 }
 
-var DOUBLE_SLASH_REGEX = /\s*[\\/]{2,}/;
+var DOUBLE_SLASH_REGEX = /^\s*[\\/]{2,}/;
 function parseAppUrl(url, locationObj) {
 
-  if (url.search(DOUBLE_SLASH_REGEX) === 0) {
+  if (DOUBLE_SLASH_REGEX.test(url)) {
     throw $locationMinErr('badpath', 'Invalid url "{0}".', url);
   }
 

test/ng/locationSpec.js

@@ -2488,6 +2488,10 @@ describe('$location', function() {
       expect(function() {
         parseLinkAndReturn(locationUrl, 'http://server/pre/\\\\other/path');
       }).toThrowMinErr('$location', 'badpath');
+
+      expect(function() {
+        parseLinkAndReturn(locationUrl, 'http://server/pre//\\//other/path');
+      }).toThrowMinErr('$location', 'badpath');
     });
 
     it('should complain if no base tag present', function() {