Support general handling of type variables by substituting types into the current context.

sdk/lib/_internal/compiler/implementation/elements/modelx.dart

 // Copyright (c) 2013, 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.
 
 library elements.modelx;
 
 import 'elements.dart';
 import '../tree/tree.dart';
 import '../util/util.dart';
 import '../resolution/resolution.dart';
@@ skipping 242 matching lines @@
   Element getOutermostEnclosingMemberOrTopLevel() {
     // TODO(lrn): Why is this called "Outermost"?
     for (Element e = this; e != null; e = e.enclosingElement) {
       if (e.isMember() || e.isTopLevel()) {
         return e;
       }
     }
     return null;
   }
 
+  ClassElement get contextClass {
+    ClassElement cls;
+    for (Element e = this; e != null; e = e.enclosingElement) {
+      if (e.isClass()) {
+        cls = e.declaration;

[karlklose, 2014/05/07 12:46:37]

Break or return value here?

[Johnni Winther, 2014/05/08 07:03:59]

No. We need the last class -- the first might be a closure class. Added a
comment.

+      }
+    }
+    return cls;
+  }
+
   /**
    * Creates the scope for this element.
    */
   Scope buildScope() => enclosingElement.buildScope();
 
   String toString() {
     // TODO(johnniwinther): Test for nullness of name, or make non-nullness an
     // invariant for all element types?
     var nameText = name != null ? name : '?';
     if (enclosingElement != null && !isTopLevel()) {
@@ skipping 1696 matching lines @@
       }
     }
   }
 
   InterfaceType createType(Link<DartType> typeArguments) {
     return new InterfaceType(this, typeArguments);
   }
 
   Link<DartType> computeTypeParameters(Compiler compiler);
 
+  InterfaceType asInstanceOf(ClassElement cls) {
+    if (cls == this) return thisType;
+    return allSupertypesAndSelf.asInstanceOf(cls);
+  }
+
   /**
    * Return [:true:] if this element is the [:Object:] class for the [compiler].
    */
   bool isObject(Compiler compiler) =>
       identical(declaration, compiler.objectClass);
 
   void ensureResolved(Compiler compiler) {
     if (resolutionState == STATE_NOT_STARTED) {
       compiler.resolver.resolveClass(this);
     }
@@ skipping 630 matching lines @@
 
   ParameterMetadataAnnotation(Metadata this.metadata);
 
   Node parseNode(DiagnosticListener listener) => metadata.expression;
 
   Token get beginToken => metadata.getBeginToken();
 
   Token get endToken => metadata.getEndToken();
 }