Fix and reenable checkbox in Polymer page set.

tools/perf/page_sets/polymer.py

Index: tools/perf/page_sets/polymer.py
diff --git a/tools/perf/page_sets/polymer.py b/tools/perf/page_sets/polymer.py
index 9a7ff97f43fd5a620c130bfd4d440ba64565f44e..76701b77d89606c9b715088e683e4d7fd340eac2 100644
--- a/tools/perf/page_sets/polymer.py
+++ b/tools/perf/page_sets/polymer.py
@@ -145,8 +145,7 @@ class PolymerSampler(PolymerPage):
         'paper-checkbox',
         'paper-fab',
         'paper-icon-button',
-        # crbug.com/394756
-        # 'paper-radio-button',
+        'paper-radio-button',
         'paper-tab',
         'paper-toggle-button',
         'x-shadow',
@@ -162,7 +161,7 @@ class PolymerSampler(PolymerPage):
     # currently active as they typically don't produce animation frames.
     element_list_query = (self.iframe_js +
         ('.contentDocument.querySelectorAll("body %s:not([disabled]):'
-         'not([active])")' % widget_type))
+         'not([active]):not([checked])")' % widget_type))
     roles_count_query = element_list_query + '.length'
     for i in range(action_runner.EvaluateJavaScript(roles_count_query)):
       element_query = element_list_query + ("[%d]" % i)
@@ -206,8 +205,7 @@ class PolymerPageSet(page_set_module.PageSet):
         'paper-checkbox',
         'paper-fab',
         'paper-icon-button',
-        # crbug.com/394756
-        # 'paper-radio-button',
+        'paper-radio-button',
         'paper-shadow',
         'paper-tabs',
         'paper-toggle-button',