[ChromiumPerf] Disable failing Polymer benchmarks

The Polymer page set is using deprecated feature (/deep/ selector)
and needs to be updated before re-enabling.

BUG=746729,750876

Change-Id: Iac5eb3651d6c22f59e18c8271c9eb5270b44c3d6
Reviewed-on: https://chromium-review.googlesource.com/594908
Commit-Queue: Victor Miura <vmiura@chromium.org>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Cr-Commit-Position: refs/heads/master@{#491571}

tools/perf/benchmarks/smoothness.py

@@ -500,7 +500,9 @@ class SmoothnessGpuRasterizationToughPinchZoomCases(_Smoothness):
     return StoryExpectations()
 
 
-@benchmark.Enabled('android')
+# This benchmark runs only on android, but is disabled because the page set
+# uses deprecated web platform features.  See http://crbug.com/750876
+@benchmark.Disabled('all')
 @benchmark.Owner(emails=['vmiura@chromium.org'])
 class SmoothnessGpuRasterizationPolymer(_Smoothness):
   """Measures rendering statistics for the Polymer cases with GPU rasterization.

tools/perf/benchmarks/thread_times.py

@@ -48,7 +48,10 @@ class ThreadTimesKeySilkCases(_ThreadTimes):
     return page_sets.KeySilkCasesStoryExpectations()
 
 
-@benchmark.Enabled('android', 'linux')
+# This benchmark runs only on android & linux, but is disabled because the page
+# set uses deprecated web platform features.  See http://crbug.com/750876
+# @benchmark.Enabled('android', 'linux')
+@benchmark.Disabled('all')
 class ThreadTimesKeyHitTestCases(_ThreadTimes):
   """Measure timeline metrics while performing smoothness action on key hit
   testing cases."""