Make TypeMask an interface and start hiding implementation details of FlatTypeMask.

sdk/lib/_internal/compiler/implementation/ssa/codegen.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 ssa;
 
 class SsaCodeGeneratorTask extends CompilerTask {
 
   final JavaScriptBackend backend;
 
@@ skipping 1675 matching lines @@
   visitLocalGet(HLocalGet node) {
     use(node.receiver);
   }
 
   visitLocalSet(HLocalSet node) {
     use(node.value);
     assignVariable(variableNames.getName(node.receiver), pop());
   }
 
   void registerForeignType(HType type) {
-    // TODO(kasperl): This looks shaky. It makes sense if the type is
-    // exact, but otherwise we should be registering more types as
-    // instantiated. We should find a way of using something along the
-    // lines of the NativeEnqueuerBase.processNativeBehavior method.
     if (type.isUnknown()) return;
     TypeMask mask = type.computeMask(compiler);
-    world.registerInstantiatedClass(mask.base.element, work.resolutionTree);
+    for (ClassElement cls in mask.containedClasses(compiler)) {
+      world.registerInstantiatedClass(cls, work.resolutionTree);
+    }
   }
 
   visitForeign(HForeign node) {
     String code = node.code.slowToString();
     List<HInstruction> inputs = node.inputs;
     if (node.isJsStatement()) {
       if (!inputs.isEmpty) {
         compiler.internalError("foreign statement with inputs: $code",
                                instruction: node);
       }
@@ skipping 1269 matching lines @@
   if (leftType.canBeNull() && rightType.canBeNull()) {
     if (left.isConstantNull() || right.isConstantNull() ||
         (leftType.isPrimitive() && leftType == rightType)) {
       return '==';
     }
     return null;
   } else {
     return '===';
   }
 }