blink_perf.canvas failing on 8 builders

Builders failed on: 
- Mac 10.11 Perf: 
  https://build.chromium.org/p/chromium.perf/builders/Mac%2010.11%20Perf
- Mac 10.12 Perf: 
  https://build.chromium.org/p/chromium.perf/builders/Mac%2010.12%20Perf
- Mac Air 10.11 Perf: 
  https://build.chromium.org/p/chromium.perf/builders/Mac%20Air%2010.11%20Perf
- Mac Pro 10.11 Perf: 
  https://build.chromium.org/p/chromium.perf/builders/Mac%20Pro%2010.11%20Perf
- Mac Retina Perf: 
  https://build.chromium.org/p/chromium.perf/builders/Mac%20Retina%20Perf
- Win 10 High-DPI Perf: 
  https://build.chromium.org/p/chromium.perf/builders/Win%2010%20High-DPI%20Perf
- Win 7 ATI GPU Perf: 
  https://build.chromium.org/p/chromium.perf/builders/Win%207%20ATI%20GPU%20Perf
- Win 7 Nvidia GPU Perf: 
  https://build.chromium.org/p/chromium.perf/builders/Win%207%20Nvidia%20GPU%20Perf


This is in the test log (from https://chromium-swarm.appspot.com/task?id=36e8b8fc011be710&refresh=10&show_raw=1): 
FATAL: Got an exception while running test.run with name=TypeError, message=Cannot read property 'dataUnion' of null
Traceback (most recent call last):
  File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/internal/story_runner.py", line 99, in _RunStoryAndProcessErrorIfNeeded
    state.RunStory(results)
  File "/b/s/w/ir/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 52, in traced_function
    return func(*args, **kwargs)
  File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/page/shared_page_state.py", line 298, in RunStory
    self._current_page, self._current_tab, results)
  File "/b/s/w/ir/third_party/catapult/common/py_trace_event/py_trace_event/trace_event_impl/decorators.py", line 52, in traced_function
    return func(*args, **kwargs)
  File "/b/s/w/ir/tools/perf/benchmarks/blink_perf.py", line 232, in ValidateAndMeasurePage
    results.current_page, metric, units, values))
  File "/b/s/w/ir/third_party/catapult/telemetry/telemetry/value/list_of_scalar_values.py", line 83, in __init__
    assert len(values) > 0
AssertionError

Not exactly sure what's causing that. Didn't see anything in //tools/perf or //third_party/WebKit/PerformanceTests/Canvas that looked suspicious.

Will disable the story that's failing.