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

BUG=673022

Review-Url: https://codereview.chromium.org/2565673003
Cr-Commit-Position: refs/heads/master@{#437982}

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

@@ -425,7 +425,7 @@ goog.require('__crWeb.message');
     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(