Disable blink_perf.canvas on linux.

This has been red going on a week now.

BUG=488059
CQ_EXTRA_TRYBOTS=tryserver.chromium.perf:linux_perf_bisect;tryserver.chromium.perf:mac_perf_bisect;tryserver.chromium.perf:win_perf_bisect;tryserver.chromium.perf:android_nexus5_perf_bisect

Review URL: https://codereview.chromium.org/1129383007

Cr-Commit-Position: refs/heads/master@{#330085}

tools/perf/benchmarks/blink_perf.py

@@ -167,7 +167,8 @@ class BlinkPerfCSS(benchmark.Benchmark):
     return CreatePageSetFromPath(path, SKIPPED_FILE)
 
 
-@benchmark.Disabled('win')  # crbug.com/455796
+@benchmark.Disabled('win',   # crbug.com/455796
+                    'linux') # crbug.com/488059
 class BlinkPerfCanvas(benchmark.Benchmark):
   tag = 'canvas'
   test = _BlinkPerfMeasurement