Filter out events jittery for single-touch gestures.

Filter out events jittery for single-touch gestures.

In the majority of cases when user taps on the screen, many touch move events
are generated from platform. These unexpected touch move events cause frequent
calling seek on media player.

It looks too sensitive compared with Android browser.

This patch dispatches first move event if distance from last pressed position
exceeds scroll threshold.

Bug: http://107.108.218.239/bugzilla/show_bug.cgi?id=13974

Reviewed by: a1.gomes, sns.park

Change-Id: Ia491beb54c1cf32df78d9af8b7e7a212c7f54e61
Signed-off-by: Sanghyup Lee <sh53.lee@samsung.com>