[Android] Turn on WebNotification runtime feature on Android
[Android] Turn on WebNotification runtime feature on Android

It's disabled for chrome on Android.
For crosswalk, it will have an implementation working with
Android Notification.

BUG=https://crosswalk-project.org/jira/browse/XWALK-94

bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk