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

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

Index: sdk/lib/_internal/compiler/implementation/elements/modelx.dart
diff --git a/sdk/lib/_internal/compiler/implementation/elements/modelx.dart b/sdk/lib/_internal/compiler/implementation/elements/modelx.dart
index 4a5ffb7e3a9c9c97c3ad625166ad4563de32c19f..2ea79f7f519c24e6a346024de611151cfa3e1d8e 100644
--- a/sdk/lib/_internal/compiler/implementation/elements/modelx.dart
+++ b/sdk/lib/_internal/compiler/implementation/elements/modelx.dart
@@ -260,6 +260,16 @@ abstract class ElementX implements Element {
     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.
    */
@@ -1976,6 +1986,11 @@ abstract class BaseClassElementX extends ElementX
 
   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].
    */