Use Polymer.dom with many dom manipulations.

tracing/tracing/ui/base/hotkey_controller_test.html

Index: tracing/tracing/ui/base/hotkey_controller_test.html
diff --git a/tracing/tracing/ui/base/hotkey_controller_test.html b/tracing/tracing/ui/base/hotkey_controller_test.html
index f5a1e3556dde05cd73223a00b8a7a521636d7604..2ef4c5bb7374687e974583e0e8d4cd46d656deef 100644
--- a/tracing/tracing/ui/base/hotkey_controller_test.html
+++ b/tracing/tracing/ui/base/hotkey_controller_test.html
@@ -57,7 +57,7 @@ tr.b.unittest.testSuite(function() {
       assert.isTrue(didGetCalled);
 
     } finally {
-      document.body.removeChild(rootElement);
+      Polymer.dom(document.body).removeChild(rootElement);
     }
   });
 
@@ -93,7 +93,7 @@ tr.b.unittest.testSuite(function() {
       rootElement.dispatchEvent(e);
       assert.isTrue(didGetCalled);
     } finally {
-      document.body.removeChild(rootElement);
+      Polymer.dom(document.body).removeChild(rootElement);
     }
   });
 
@@ -130,7 +130,7 @@ tr.b.unittest.testSuite(function() {
       inputEl.dispatchEvent(e);
       assert.isFalse(didGetCalled);
     } finally {
-      document.body.removeChild(rootElement);
+      Polymer.dom(document.body).removeChild(rootElement);
     }
   });