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

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

Index: pkg/compiler/lib/src/parser/member_listener.dart
diff --git a/pkg/compiler/lib/src/parser/member_listener.dart b/pkg/compiler/lib/src/parser/member_listener.dart
index 202fba311c4e9e139b42f1785a3aac1ca3597010..2346ebff1b1a389cfe186f075d0ead25dd8cf511 100644
--- a/pkg/compiler/lib/src/parser/member_listener.dart
+++ b/pkg/compiler/lib/src/parser/member_listener.dart
@@ -156,6 +156,10 @@ class MemberListener extends NodeListener {
   @override
   void endMetadata(Token beginToken, Token periodBeforeName, Token endToken) {
     super.endMetadata(beginToken, periodBeforeName, endToken);
-    pushMetadata(new PartialMetadataAnnotation(beginToken, endToken));
+    // TODO(paulberry,ahe): type variable metadata should not be ignored.  See
+    // dartbug.com/5841.
+    if (!inTypeVariable) {
+      pushMetadata(new PartialMetadataAnnotation(beginToken, endToken));
+    }
   }
 }