Remove use of deprecated mirror functions from Polymer.

pkg/polymer/lib/src/loader.dart

Index: pkg/polymer/lib/src/loader.dart
diff --git a/pkg/polymer/lib/src/loader.dart b/pkg/polymer/lib/src/loader.dart
index 47fa3108ddbce493472995e9056357d16d8ff0f3..5ee0915077cb1cad0399797b7ce862ea24fc8374 100644
--- a/pkg/polymer/lib/src/loader.dart
+++ b/pkg/polymer/lib/src/loader.dart
@@ -171,11 +171,11 @@ void _loadLibrary(String uriString) {
   }
 
   // Search top-level functions marked with @initMethod
-  for (var f in lib.functions.values) {
+  for (var f in lib.declarations.values.where((d) => d is MethodMirror)) {
     _maybeInvoke(lib, f);
   }
 
-  for (var c in lib.classes.values) {
+  for (var c in lib.declarations.values.where((d) => d is ClassMirror)) {
     // Search for @CustomTag on classes
     for (var m in c.metadata) {
       var meta = m.reflectee;