Suppress WebglConformance shader-with-non-reserved-words on Mac/nVidia/Debug

WebglConformance_conformance_glsl_misc_shader_with_non_reserved_words fails
at Mac FYI Retina Debug (NVIDIA) bot

Bug: 948218
Change-Id: I057b5d431af758a8b85c301490891ef32e04b91f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1547948Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Maggie Chen <magchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#646448}

content/test/gpu/gpu_tests/webgl_conformance_expectations.py

@@ -557,8 +557,8 @@ class WebGLConformanceExpectations(GpuTestExpectations):
         ['mac', ('nvidia', 0xfe9)], bug=784817)
     self.Fail('conformance/uniforms/uniform-samplers-test.html',
         ['mac', 'debug', ('nvidia', 0xfe9)], bug=871352)
-    self.Flaky('conformance/glsl/misc/shader-with-non-reserved-words.html',
-        ['mac', 'debug', ('nvidia', 0xfe9)], bug=929009)
+    self.Fail('conformance/glsl/misc/shader-with-non-reserved-words.html',
+        ['mac', 'debug', ('nvidia', 0xfe9)], bug=948218)
 
     # Already fixed with Mesa 17.1.6
     self.Fail('conformance/extensions/webgl-compressed-texture-astc.html',