Implemented selection by doubleTap in WebKit.

Implemented selection by doubleTap in WebKit.

[Title] Implemented selection by doubleTap in WebKit.
[Issue#] N/A
[Problem] When doubleTap on any text of email composor, sometimes selection is not working properly.
[Cause] Current, selection by doubleTap is implemented in Email.
        So, when doubleTap on any text of email composor,
        selection routine from email is called and tap is performed twice from WebKit.
        Tap should not be performed in case of doubleTap from email.
[Solution] Moved selection by doubleTap to WebKit.

Change-Id: I4440325118c302b2473a9b1f23734cf060f71eb3