Re-land "Add support for metadata on type variables to Fasta parser." (with fixes).

pkg/compiler/lib/src/parser/node_listener.dart

Index: pkg/compiler/lib/src/parser/node_listener.dart
diff --git a/pkg/compiler/lib/src/parser/node_listener.dart b/pkg/compiler/lib/src/parser/node_listener.dart
index 81a29c31764f884f35909c2f6baf63a76feb9faf..e004b59755c1bc9148ee3b353fc558eb31681353 100644
--- a/pkg/compiler/lib/src/parser/node_listener.dart
+++ b/pkg/compiler/lib/src/parser/node_listener.dart
@@ -1009,6 +1009,18 @@ class NodeListener extends ElementListener {
   }
 
   @override
+  void endTypeVariable(Token token, Token extendsOrSuper) {
+    inTypeVariable = false;
+    NominalTypeAnnotation bound = popNode();
+    Identifier name = popNode();
+    // TODO(paulberry): type variable metadata should not be ignored.  See
+    // dartbug.com/5841.
+    popNode(); // Metadata
+    pushNode(new TypeVariable(name, extendsOrSuper, bound));
+    rejectBuiltInIdentifier(name);
+  }
+
+  @override
   void log(message) {
     reporter.log(message);
   }