Bug 721006 - Crash when setting a very large document.title. r=mfinkle

mobile/android/chrome/content/browser.js

@@ -1785,7 +1785,7 @@ Tab.prototype = {
           gecko: {
             type: "DOMTitleChanged",
             tabID: this.id,
-            title: aEvent.target.title
+            title: aEvent.target.title.substring(0, 255)
           }
         });
         break;