[polymer] fix editor hints -- query/queryAll and unused imports

pkg/polymer/test/prop_attr_bind_reflection_test.dart

Index: pkg/polymer/test/prop_attr_bind_reflection_test.dart
diff --git a/pkg/polymer/test/prop_attr_bind_reflection_test.dart b/pkg/polymer/test/prop_attr_bind_reflection_test.dart
index 554bbfb691cee835f61b2dd4aa0713824102e199..bfe16bfb791aac961669538979d5aa38cfc169b8 100644
--- a/pkg/polymer/test/prop_attr_bind_reflection_test.dart
+++ b/pkg/polymer/test/prop_attr_bind_reflection_test.dart
@@ -33,7 +33,8 @@ main() {
   setUp(() => Polymer.onReady);
 
   test('attribute reflected to property name', () {
-    var child = query('my-element').shadowRoot.query('my-child-element');
+    var child = querySelector('my-element')
+        .shadowRoot.querySelector('my-child-element');
     expect(child.lowercase, 11);
     expect(child.camelCase, 11);