Suppress two WebGL tests on Linux Intel bot.

They are only failing on the experimental bot, which is Mesa 18.0.5, and are
passing on Mesa 17.1.4.

Unfortunately our test expectations don't support driver versions.

BUG=928530
TEST=Linux Intel experimental bot
R=kbr@chromium.org

Change-Id: I03f64ec71e2c59541a9b44257128f1ec22293ac5
Reviewed-on: https://chromium-review.googlesource.com/c/1493443
Commit-Queue: Zhenyao Mo <zmo@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Auto-Submit: Zhenyao Mo <zmo@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636322}

content/test/gpu/gpu_tests/webgl_conformance_expectations.py

@@ -643,6 +643,13 @@ class WebGLConformanceExpectations(GpuTestExpectations):
         'draw-webgl-to-canvas-2d-repeatedly.html',
         ['linux', 'amd', 'passthrough'], bug=906066)
 
+    # The following two tests only fail on Linux/Intel with Mesa 18.0.5,
+    # not on Mesa 17.1.4 with the same Intel HD 630 GPU.
+    self.Fail('conformance/programs/program-test.html',
+        ['linux', 'intel'], bug=928530)
+    self.Fail('conformance/uniforms/uniform-default-values.html',
+        ['linux', 'intel'], bug=928530)
+
     ####################
     # Android failures #
     ####################