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

pkg/polymer/lib/src/build/build_filter.dart

Index: pkg/polymer/lib/src/build/build_filter.dart
diff --git a/pkg/polymer/lib/src/build/build_filter.dart b/pkg/polymer/lib/src/build/build_filter.dart
index 9bc8bd4fe0a7fbb14b4e506fd58b02255916cb55..5314a0d8047a9dd90d7be20b93debc5faf124af3 100644
--- a/pkg/polymer/lib/src/build/build_filter.dart
+++ b/pkg/polymer/lib/src/build/build_filter.dart
@@ -39,7 +39,7 @@ class BuildFilter extends Transformer with PolymerTransformer {
     return readPrimaryAsHtml(transform).then((document) {
       // Keep .html files that don't use polymer, since the app developer might
       // have non-polymer entrypoints.
-      if (document.queryAll('polymer-element').isEmpty) {
+      if (document.querySelectorAll('polymer-element').isEmpty) {
         transform.addOutput(transform.primaryInput);
       }
     });