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

pkg/polymer/test/custom_event_test.dart

Index: pkg/polymer/test/custom_event_test.dart
diff --git a/pkg/polymer/test/custom_event_test.dart b/pkg/polymer/test/custom_event_test.dart
index 08c45af96fbaa388acc9f850ba4e065f626ef363..b5840294848533777bec13dbac28def0c4a70441 100644
--- a/pkg/polymer/test/custom_event_test.dart
+++ b/pkg/polymer/test/custom_event_test.dart
@@ -35,7 +35,7 @@ class FooBar extends PolymerElement {
 class TestCustomEvent extends PolymerElement {
   TestCustomEvent.created() : super.created();
 
-  get fooBar => getShadowRoot('test-custom-event').query('foo-bar');
+  get fooBar => getShadowRoot('test-custom-event').querySelector('foo-bar');
 
   final events = [];
   fooHandler(e) => events.add(['foo', e]);
@@ -49,7 +49,7 @@ main() {
   setUp(() => Polymer.onReady);
 
   test('custom event', () {
-    final testComp = query('test-custom-event');
+    final testComp = querySelector('test-custom-event');
     final fooBar = testComp.fooBar;
 
     final binding = nodeBind(fooBar).bindings['on-barbaz'];