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

pkg/polymer/test/prop_attr_reflection_test.dart

Index: pkg/polymer/test/prop_attr_reflection_test.dart
diff --git a/pkg/polymer/test/prop_attr_reflection_test.dart b/pkg/polymer/test/prop_attr_reflection_test.dart
index 37562dad192a8af0796e42b32274fc29ba2b9047..79b9c8eb55be72baf4442909d72842bdea7108d5 100644
--- a/pkg/polymer/test/prop_attr_reflection_test.dart
+++ b/pkg/polymer/test/prop_attr_reflection_test.dart
@@ -52,9 +52,9 @@ main() {
   Polymer.register('x-compose', XCompose);
 
   test('property attribute reflection', () {
-    var xcompose = query('x-compose');
-    var xfoo = query('x-foo');
-    var xbar = query('x-bar');
+    var xcompose = querySelector('x-compose');
+    var xfoo = querySelector('x-foo');
+    var xbar = querySelector('x-bar');
     xfoo.foo = 5;
     return onAttributeChange(xfoo).then((_) {
       expect(xcompose.$['bar'].attributes.containsKey('zim'), false,