Support type variables as expressions.

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

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of resolution;
 
 abstract class TreeElements {
   Element get currentElement;
   Set<Node> get superUses;
 
@@ skipping 2180 matching lines @@
     if (!Elements.isUnresolved(target)) {
       if (target.isAbstractField()) {
         AbstractFieldElement field = target;
         target = field.getter;
         if (target == null && !inInstanceContext) {
           compiler.backend.registerThrowNoSuchMethod(mapping);
           target =
               warnAndCreateErroneousElement(node.selector, field.name,
                                             MessageKind.CANNOT_RESOLVE_GETTER);
         }
+      } else if (target.isTypeVariable()) {
+        ClassElement cls = target.getEnclosingClass();
+        assert(enclosingElement.getEnclosingClass() == cls);
+        compiler.world.registerClassUsingVariableExpression(cls);
+        compiler.backend.registerTypeVariableExpression(mapping);
       } else if (target.impliesType() && !sendIsMemberAccess) {
         compiler.backend.registerTypeLiteral(mapping);
       }
     }
 
     bool resolvedArguments = false;
     if (node.isOperator) {
       String operatorString = node.selector.asOperator().source.stringValue;
       if (operatorString == 'is' || operatorString == 'as') {
         assert(node.arguments.tail.isEmpty);
@@ skipping 1631 matching lines @@
     return e;
   }
 
   /// Assumed to be called by [resolveRedirectingFactory].
   Element visitReturn(Return node) {
     Node expression = node.expression;
     return finishConstructorReference(visit(expression),
                                       expression, expression);
   }
 }