Fix window.history.go() with no parameter.

ios/web/web_state/js/resources/core.js

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file adheres to closure-compiler conventions in order to enable
 // compilation with ADVANCED_OPTIMIZATIONS. In particular, members that are to
 // be accessed externally should be specified in this['style'] as opposed to
 // this.style because member identifiers are minified by default.
 // See http://goo.gl/FwOgy
 
@@ skipping 407 matching lines @@
   };
 
   // Intercept window.history methods to call back/forward natively.
   window.history.back = function() {
     invokeOnHost_({'command': 'window.history.back'});
   };
   window.history.forward = function() {
     invokeOnHost_({'command': 'window.history.forward'});
   };
   window.history.go = function(delta) {
-    invokeOnHost_({'command': 'window.history.go', 'value': delta});
+    invokeOnHost_({'command': 'window.history.go', 'value': delta | 0});
   };
   window.history.pushState = function(stateObject, pageTitle, pageUrl) {
     __gCrWeb.message.invokeOnHost(
         {'command': 'window.history.willChangeState'});
     // Calling stringify() on undefined causes a JSON parse error.
     var serializedState =
         typeof(stateObject) == 'undefined' ? '' :
             __gCrWeb.common.JSONStringify(stateObject);
     pageUrl = pageUrl || window.location.href;
     originalWindowHistoryPushState.call(history, stateObject,
@@ skipping 230 matching lines @@
       });
     }, false);
 
     addFormEventListeners_();
 
     return true;
   };
 
   __gCrWeb.core.documentInject();
 }());  // End of anonymous object