Add error handling to RenderTarget creation.

 * RenderTarget9/11 don't create any resources themselves anymore.
 * Pass the real internal format to RenderTarget creation so that it is
   not lost by converting to D3D formats and back.

BUG=angle:520

Change-Id: If420970d42f0bf6ce392d64f9cb7efa4df0b8f8e
Reviewed-on: https://chromium-review.googlesource.com/222838
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
Remove the gl::error function.

BUG=angle:520

Change-Id: Iefd4345aa347041143d5452cc2fcf48c071d494b
Reviewed-on: https://chromium-review.googlesource.com/222839
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>