We don't support populating a texture from an EGLImage, but
this feature is in use by games. Instead, populate the texture
with null data. In the future, improve this by reading back the
data.

Test: Capture and play back first 1200 frames of COD.
Bug: b/164426913
Bug: angleproject:4048
Change-Id: Ic8c6bdf3c359c89e647c28b8c57b7218bdf05b15
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2355705Reviewed-by: Manh Nguyen <nguyenmh@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Cody Northrop <cnorthrop@google.com>