Disable failing blink_perf.canvas stories on Webview too

Even though they're failing on 5X webview and they're disabled on 5X,
there's a bug where 5X webview isn't matching the 5X test condition
(https://github.com/catapult-project/catapult/issues/4045).

TBR=ashleymarie@chromium.org
NOTRY=true

Bug: 784540
Change-Id: I100929183b15c1d84ff4e0cecddb15236644bb84
Reviewed-on: https://chromium-review.googlesource.com/775433Reviewed-by: Charlie Andrews <charliea@chromium.org>
Commit-Queue: Charlie Andrews <charliea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517137}

tools/perf/benchmarks/blink_perf.py

@@ -436,12 +436,14 @@ class BlinkPerfCanvas(_BlinkPerfBenchmark):
         self.DisableStory(
             'draw-static-canvas-2d-to-hw-accelerated-canvas-2d.html',
             [story.expectations.ANDROID_NEXUS5,
-             story.expectations.ANDROID_NEXUS5X],
+             story.expectations.ANDROID_NEXUS5X,
+             story.expectations.ANDROID_WEBVIEW],
             'crbug.com/784540')
         self.DisableStory(
             'draw-dynamic-canvas-2d-to-hw-accelerated-canvas-2d.html',
             [story.expectations.ANDROID_NEXUS5,
-             story.expectations.ANDROID_NEXUS5X],
+             story.expectations.ANDROID_NEXUS5X,
+             story.expectations.ANDROID_WEBVIEW],
             'crbug.com/784540')
     return StoryExpectations()