[NaCl SDK] Fix some bugs in the bullet demo

* Use the correct mouse position when the render window isn't at 0x0
  (event.client{X,Y} are relative to the viewport).
* Don't select text when dragging in the render viewport (use preventDefault).
* Drop any held objects when the mouse leaves the render viewport (listen for
  "mouseleave")

BUG=none
R=sbc@chromium.org

Review URL: https://codereview.chromium.org/48903018

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232441 0039d316-1c4b-4281-b951-d872f2087c98
Enable webapps by default on stable channel

BUG=266403

Review URL: https://codereview.chromium.org/54583004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232442 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232441
Revert 227677 - Trigger visibilitychange events on app container state changes

Original CL: https://codereview.chromium.org/23473005/

BUG=312430

Review URL: https://codereview.chromium.org/54643005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232443 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232443