[webapi][XWALK-2372] Update screen orientation tests

to reflect Chromium 38 implementation at XWALK-2431
https://w3c.github.io/screen-orientation/
[usecase][XWALK-2372] Update screen orientation tests

to reflect Chromium 38 implementation at XWALK-2431
https://w3c.github.io/screen-orientation/
Merge pull request #860 from zqzhang/screen-orientation

[XWALK-2372] Update screen orientation tests