[Telemetry] Expect to skip smoothness.maps on low-end devices

tools/perf/benchmarks/webgl_expectations.py

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from telemetry.page import test_expectations
 
 class WebGLExpectations(test_expectations.TestExpectations):
   def SetExpectations(self):
     self.Skip('*', ['arm', 'broadcom', 'hisilicon', 'imagination', 'qualcomm',
                     'vivante'], bug=462729)
+
+
+class WebGLLowEndExpectations(test_expectations.TestExpectations):
+  """Defines expectations to skip intensive tests on low-end devices."""
+  def SetExpectations(self):
+    self.Skip('*', ['arm'], bug=464731)