[Telemetry] Disable spaceport and tough_canvas_cases on mac.

tools/perf/benchmarks/smoothness.py

Index: tools/perf/benchmarks/smoothness.py
diff --git a/tools/perf/benchmarks/smoothness.py b/tools/perf/benchmarks/smoothness.py
index 0d3a8364f3b94e3b1de65768a09acd0c6f78391a..25e69825d6caefa251f6d39a2167c8eeb5880f28 100644
--- a/tools/perf/benchmarks/smoothness.py
+++ b/tools/perf/benchmarks/smoothness.py
@@ -1,6 +1,9 @@
 # Copyright (c) 2013 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.
+
+import sys
+
 from telemetry import test
 
 from measurements import smoothness
@@ -16,6 +19,7 @@ class SmoothnessTop25(test.Test):
 
 class SmoothnessToughCanvasCases(test.Test):
   test = smoothness.Smoothness
+  enabled = sys.platform != 'darwin'
   page_set = 'page_sets/tough_canvas_cases.json'