Fix bug 4111271 and bug 4077526 - WebView touch event handling when

WebCore is too slow

Make sure that we can recover properly from a bad gesture with missing
events that never come back from webcore. Lower timeout to 1 second.

Confirm movement on touch event enqueue so that we don't get phantom
taps or long presses when webcore is slow to respond.

Add sanity check in ScaleGestureDetector to end a gesture early on a
bad MotionEvent stream rather than throwing up.

Change-Id: I69690409d7edd6b4320dbcf3b052aba4023360fe