Update the getRenderTarget functions to return gl::Error objects.

BUG=angle:520

Change-Id: If1f4f71972b669704eff70b5f60927d8e6ac07b3
Reviewed-on: https://chromium-review.googlesource.com/218767
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
Removed declaration of getAttachedShaders() without implementation.

Found while working on BUG=angle:751

BUG=angle:751

Change-Id: I8a5c5383f88ecb379395d1a23e36148145ebe34d
Reviewed-on: https://chromium-review.googlesource.com/224090
Tested-by: Tibor Ouden, den <tibordenouden@gmail.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Use a constant for the number of faces in a cube map.

BUG=angle:520

Change-Id: Ia35103059526aff2fc1b29a160d8471f4b5cbd42
Reviewed-on: https://chromium-review.googlesource.com/223107
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
Defer the creation of Blit9's geometry and return Errors if it fails.

BUG=angle:520

Change-Id: I5e51fec38c513419beea5ff612a6ec2fb0e81a26
Reviewed-on: https://chromium-review.googlesource.com/218768
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
Added IInspectable EGLNativeWindowType and ICoreWindow support

Change-Id: I6dd7fef72a73572d4a3deda7ce36a11da3a75c81
Reviewed-on: https://chromium-review.googlesource.com/224366
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>