Split HForeign into HForeignCode and abstract base class.

pkg/compiler/lib/src/ssa/ssa_tracer.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 ssa.tracer;
 
 import 'dart:async' show EventSink;
 
 import 'ssa.dart';
 import '../js_backend/js_backend.dart';
@@ skipping 313 matching lines @@
   String visitInvokeSuper(HInvokeSuper invoke) {
     String target = invoke.element.name;
     return visitGenericInvoke("Invoke super", target, invoke.inputs);
   }
 
   String visitInvokeConstructorBody(HInvokeConstructorBody invoke) {
     String target = invoke.element.name;
     return visitGenericInvoke("Invoke constructor body", target, invoke.inputs);
   }
 
-  String visitForeign(HForeign foreign) {
-    return visitGenericInvoke("Foreign", "${foreign.codeTemplate.ast}", foreign.inputs);
+  String visitForeignCode(HForeignCode foreign) {
+    return visitGenericInvoke("Foreign", "${foreign.codeTemplate.ast}",
+                              foreign.inputs);
   }
 
   String visitForeignNew(HForeignNew node) {
     return visitGenericInvoke("New",
                               "${node.element.name}",
                               node.inputs);
   }
 
   String visitLess(HLess node) => handleInvokeBinary(node, '<');
   String visitLessEqual(HLessEqual node) => handleInvokeBinary(node, '<=');
@@ skipping 176 matching lines @@
   }
 
   String visitAwait(HAwait node) {
     return "await ${temporaryId(node.inputs[0])}";
   }
 
   String visitYield(HYield node) {
     return "yield${node.hasStar ? "*" : ""} ${temporaryId(node.inputs[0])}";
   }
 }