[Android] Fix that multi touch on Android before 4.2.2 will crash

It's because the difference in android.view.ScaleGestureDetector
between 4.2.2 and 4.2.1.
In 4.2.1, the mCurrTime in ScaleGestureDetector is not set in any
place, so it's always zero.
Chromium's GestureDetector will use the eventTime from
ScaleGestureDetector to do vsync, which leads to assertion failure.

Fix by using overwritten ScaleGestureDetector for android before
4.2.2

BUG=https://crosswalk-project.org/jira/browse/XWALK-458