Clean and enable NoLeakingFragments multiview test
Clean and enable NoLeakingFragments multiview test

Use helper to create multiview backing textures in NoLeakingFragments
test instead of doing FBO attachments twice.

The test seems to pass on Windows after the recent fixes that have
been done to the tests, or possibly due to other earlier fixes.

BUG=angleproject:2687
TEST=angle_end2end_tests

Change-Id: I6015a5b44fdd06faf7b9375bad501355be8d7732
Reviewed-on: https://chromium-review.googlesource.com/1184713
Reviewed-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>
Commit-Queue: Olli Etuaho <38ae6c0e2772a20e8e989f80cb8c99d274e44242@nvidia.com>

ppy/angle,ppy/angle,ppy/angle,ppy/angle