[telemetry] Sort imports in Telemetry and its dependents.

tools/perf/benchmarks/task_execution_time.py

 # Copyright 2014 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 import benchmark
+
 from measurements import task_execution_time
 import page_sets
-from telemetry import benchmark
 
 
 @benchmark.Enabled('android')
 class TaskExecutionTimeKeyMobileSites(benchmark.Benchmark):
 
   """Measures task execution statistics while scrolling down key mobile sites.
 
   http://www.chromium.org/developers/design-documents/rendering-benchmarks
   """
 
@@ skipping 28 matching lines @@
 
   http://www.chromium.org/developers/design-documents/rendering-benchmarks.
   """
 
   test = task_execution_time.TaskExecutionTime
   page_set = page_sets.PathologicalMobileSitesPageSet
 
   @classmethod
   def Name(cls):
     return 'task_execution_time.pathological_mobile_sites'