[Extensions] Fix entry points for Screen Orientation Extension

After commit 856353beba8a8318c51da3d672af187d7fd58ada, entitled
"[Extensions] Add a setter callback accessor to trampolines",
we can now use screen.onorientationchange as a valid entry point.
Merge pull request #1481 from jeez/fix-screen-orientation

[Extensions] Fix entry points for Screen Orientation Extension
Fix orientation sometimes getting stuck in current orientation after unlock

While we are locked the display_.rotation() can get out of sync with the
actual device orientation, so we need to find the best orientation given
the actual orientation, not the old one.
Merge pull request #1486 from kenchris/stuck

Fix orientation sometimes getting stuck in current orientation after unlock
Make sure screen.orientation is always valid

If the orientation has not been set by the extension yet, query it
synchronously.
Merge pull request #1488 from kenchris/sync

Make sure screen.orientation is always valid
Bump version to 4.32.71.0
Implement Screen Orientation API through extension (Part 1)

Spec: https://dvcs.w3.org/hg/screen-orientation/raw-file/tip/Overview.html

This patch implemented lockOrientation and unlockOrientation API through extension.
And the followed patchs will implement onorientationchange event.

Test: http://jsbin.com/IJapIVE/4

BUG=https://crosswalk-project.org/jira/browse/XWALK-162