chore($location): drop bugus error

we can never get to this state, so dropping the error

docs/content/error/location/istart.ngdoc

@@ -1,4 +0,0 @@
-@ngdoc error
-@name $location:istart
-@fullName Invalid URL
-@description

src/ng/location.js

@@ -161,9 +161,6 @@ function LocationHashbangUrl(appBase, hashPrefix) {
    */
   this.$$parse = function(url) {
     var withoutBaseUrl = beginsWith(appBase, url) || beginsWith(appBaseNoFile, url);
-    if (!isString(withoutBaseUrl)) {
-      throw $locationMinErr('istart', 'Invalid url "{0}", does not start with "{1}".', url, appBase);
-    }
     var withoutHashUrl = withoutBaseUrl.charAt(0) == '#'
         ? beginsWith(hashPrefix, withoutBaseUrl)
         : (this.$$html5)

test/ng/locationSpec.js

@@ -338,13 +338,6 @@ describe('$location', function() {
     });
 
 
-    it('should throw error when invalid server url given', function() {
-      expect(function() {
-        url.$$parse('http://server.org/path#/path');
-      }).toThrow('[$location:istart] Invalid url "http://server.org/path#/path", does not start with "http://www.server.org:1234/base".');
-    });
-
-
     it('should throw error when invalid hashbang prefix given', function() {
       expect(function() {
         url.$$parse('http://www.server.org:1234/base#/path');