Support for generic type variables and unresolved types added.

lib/compiler/implementation/dart_backend/backend.dart

Index: lib/compiler/implementation/dart_backend/backend.dart
diff --git a/lib/compiler/implementation/dart_backend/backend.dart b/lib/compiler/implementation/dart_backend/backend.dart
index e4adcc3786cc0a9a2228cfa841561f44a1ff41bc..a896995c3fefa1892d43c17421cce5ac131b485d 100644
--- a/lib/compiler/implementation/dart_backend/backend.dart
+++ b/lib/compiler/implementation/dart_backend/backend.dart
@@ -157,6 +157,8 @@ class ReferencedElementCollector extends AbstractVisitor {
   }
 
   void collect() {
-    element.parseNode(compiler).accept(this);
+    compiler.withCurrentElement(element, () {
+      element.parseNode(compiler).accept(this);
+    });
   }
 }