[Android] Implement the onReceivedError callback.

Add the implementation of onReceivedError callback for XWalkClient
to fix the testUrl test case failed in crosswalk-cordova-android.
And remove error code from XWalkClient, which is originally from
AOSP WebView.
Merge pull request #1280 from junmin-zhu/error

[Android] Implement the onReceivedError callback.