DO NOT MERGE Set the initial scroll position for RTL.

 Bug 5268793
 Webkit knows about the correct initial position for web pages.
 On initial show, scroll to the webkit position.

 Cherry-picked from master CL: I2537b84a

 External WebKit CL: I6a91b97f

Change-Id: I2537b84a30a26a79a8a0f23fe62b9ed757f9c5a4
3 files changed