Fix that onNewIntent in CordovaWebView should return boolean as in XWalkView

onNewIntent in XWalkView is introduced by Notification API, it needs
return boolean to identify the intent is consumed or not.

BUG=https://crosswalk-project.org/jira/browse/XWALK-1072
Merge pull request #96 from wang16/xwalk

Fix that onNewIntent in CordovaWebView should return boolean as in XWalk...