Merge "HWUI: do not call glCopyTexSubImage2D on empty area." into nyc-dev
am: e4e240f13f

* commit 'e4e240f13f6c64049ef346b27d1cf78699fa800e':
  HWUI: do not call glCopyTexSubImage2D on empty area.

Change-Id: I937a56237844281af77b3018418378acc7f3eba7