Mark several WebGL conformance tests Flaky.

conformance/extensions/oes-texture-float-with-video.html
conformance/textures/image_bitmap_from_video/*
conformance/textures/video/*

On Win10 NVIDIA Quadro P400 D3D9

BUG=750896
TBR=kbr@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
Change-Id: I56d7e5e5b052d351fe30b0d775da9bf431be8d23
Reviewed-on: https://chromium-review.googlesource.com/595158
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491138}

content/test/gpu/gpu_tests/webgl_conformance_expectations.py

@@ -226,12 +226,18 @@ class WebGLConformanceExpectations(GpuTestExpectations):
     self.Fail('conformance/canvas/' +
         'framebuffer-bindings-affected-by-to-data-url.html',
         ['win10', ('nvidia', 0x1cb3), 'd3d9'], bug=680754)
+    self.Flaky('conformance/extensions/oes-texture-float-with-video.html',
+        ['win10', ('nvidia', 0x1cb3), 'd3d9'], bug=750896)
     self.Fail('conformance/limits/gl-max-texture-dimensions.html',
         ['win10', ('nvidia', 0x1cb3)], bug=715001)
     self.Fail('conformance/ogles/GL/atan/atan_001_to_008.html',
         ['win10', ('nvidia', 0x1cb3), 'd3d9'], bug=737018)
     self.Fail('conformance/ogles/GL/cos/cos_001_to_006.html',
         ['win10', ('nvidia', 0x1cb3), 'd3d9'], bug=680754)
+    self.Flaky('conformance/textures/image_bitmap_from_video/*',
+        ['win10', ('nvidia', 0x1cb3), 'd3d9'], bug=750896)
+    self.Flaky('conformance/textures/video/*',
+        ['win10', ('nvidia', 0x1cb3), 'd3d9'], bug=750896)
 
     # Win10 / NVIDIA Quadro P400 failures
     self.Flaky('conformance/textures/image_bitmap_from_video/' +