Add TypeVariable object on runtime to support reflection on type variables.

sdk/lib/_internal/compiler/implementation/resolution/members.dart

Index: sdk/lib/_internal/compiler/implementation/resolution/members.dart
diff --git a/sdk/lib/_internal/compiler/implementation/resolution/members.dart b/sdk/lib/_internal/compiler/implementation/resolution/members.dart
index af4208d99a8d82be92939d07090a6f0739349aa1..d0285e42d75b46310943230b3da2403bbbaf567d 100644
--- a/sdk/lib/_internal/compiler/implementation/resolution/members.dart
+++ b/sdk/lib/_internal/compiler/implementation/resolution/members.dart
@@ -525,7 +525,7 @@ class ResolverTask extends CompilerTask {
     return result;
   }
 
-  void resolveRedirectionChain(FunctionElement constructor, Node node) {
+  void resolveRedirectionChain(FunctionElement constructor, Spannable node) {
     FunctionElementX current = constructor;
     List<Element> seen = new List<Element>();
     // Follow the chain of redirections and check for cycles.
@@ -1078,7 +1078,7 @@ class ResolverTask extends CompilerTask {
     }));
   }
 
-  error(Node node, MessageKind kind, [arguments = const {}]) {
+  error(Spannable node, MessageKind kind, [arguments = const {}]) {
     // TODO(ahe): Make non-fatal.
     compiler.reportFatalError(node, kind, arguments);
   }