BUG=angleproject:1002

The last patch added new tests which failed on some Intel Win7
machines. This was due to a driver bug. Windows Updates have
been applied to the failing machine, and the tests now pass.

Changes between second and current (third) failed 16-bit patch:
- Reenable usage of 16-bit DXGI textures on all Intel cards
- Disable 16bpp tests on Intel D3D11 until the bots are updated
- Updated Win7 test machine. Tests now pass

Changes between first and second failed 16-bit patch:
- Disabled usage of 16-bit DXGI textures on all Intel cards
- Added DXGI->GL conversion entries for 16-bit formats, which
  fixes FBO readback issues. The ES CTS and dEQP tests which
  failed with the last patch now pass.

Change-Id: Id8ea89bfbc450beea54afdd398956bc97ecf3c01
Reviewed-on: https://chromium-review.googlesource.com/275082Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Austin Kinross <aukinros@microsoft.com>