Fix some users of removed mirror API.

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 eb0a7269c46b61897f9ea52a6e8225981fce697e..5610cfb4e64d0f877c8d7d3b8e1bc603e89e0d1c 100644
--- a/pkg/polymer/lib/src/loader.dart
+++ b/pkg/polymer/lib/src/loader.dart
@@ -169,11 +169,11 @@ 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;