Suppress flaky Webgl test

WebglConformance_conformance_textures_video_tex_2d_rgba_rgba_unsigned_short_5_5_5_1
is flaky on Android Android Release (Nexus 5X). Add a suppression.

BUG=907512
TBR=kbr@chromium.org

Change-Id: I13c43db1d7f9ee216e250e861d16c1a4879dbe5e
Reviewed-on: https://chromium-review.googlesource.com/c/1346870Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Commit-Queue: Robert Kroeger <rjkroege@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610123}

content/test/gpu/gpu_tests/webgl_conformance_expectations.py

@@ -707,6 +707,9 @@ class WebGLConformanceExpectations(GpuTestExpectations):
     self.Skip('conformance/textures/misc/texture-npot-video.html',
         ['android', 'android-webview-instrumentation', 'no_passthrough'],
               bug=352645)
+    self.Flaky('conformance/textures/video/' +
+        'tex-2d-rgba-rgba-unsigned_short_5_5_5_1.html',
+        ['android', 'release'], bug=907512)
 
     # These video tests appear to be flaky.
     self.Flaky('conformance/textures/video/' +
@@ -894,9 +897,6 @@ class WebGLConformanceExpectations(GpuTestExpectations):
     self.Flaky('conformance/textures/image_bitmap_from_video/' +
         'tex-2d-rgb-rgb-unsigned_short_5_6_5.html', ['android', 'nvidia'],
         bug=891456)
-    self.Flaky('conformance/textures/video/' +
-        'tex-2d-rgba-rgba-unsigned_short_5_5_5_1.html',
-        ['android', 'release', 'nvidia'], bug=906158)
 
     # Flaky timeout on android_n5x_swarming_rel and
     # android-marshmallow-arm64-rel.