Remove supressions for rebaselined gpu pixel tests

Affected tests:
Pixel_OffscreenCanvasTransferToImageBitmap
Pixel_OffscreenCanvasTransferToImageBitmapWorker

BUG=696224, 585607
TBR=xlai@chromium.org
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2804323002
Cr-Commit-Position: refs/heads/master@{#462991}
1 file changed