cps-ir: Support foreign code.

pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.dart

 // Copyright (c) 2014, 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 tree_ir.optimization.statement_rewriter;
 
 import 'optimization.dart' show Pass;
 import '../tree_ir_nodes.dart';
 
 /**
@@ skipping 934 matching lines @@
     return false;
   }
 
   Expression makeCondition(Expression e, bool polarity) {
     return polarity ? e : new Not(e);
   }
 
   Statement getBranch(If node, bool polarity) {
     return polarity ? node.thenStatement : node.elseStatement;
   }
+
+  @override
+  Expression visitForeignExpression(ForeignExpression node) {
+    _rewriteList(node.arguments);
+    return node;
+  }
+
+  @override
+  Statement visitForeignStatement(ForeignStatement node) {
+    _rewriteList(node.arguments);
+    return node;
+  }
 }
 
 /// Result of combining two expressions, with the potential for reverting the
 /// combination.
 ///
 /// Reverting a combination is done by calling [uncombine]. In this case,
 /// both the original expressions should remain in the tree, and the [combined]
 /// expression should be orphaned.
 ///
 /// Explicitly reverting a combination is necessary to maintain variable
@@ skipping 61 matching lines @@
   IsVariableUsedVisitor(this.variable);
 
   visitVariableUse(VariableUse node) {
     if (node.variable == variable) {
       wasFound = true;
     }
   }
 
   visitInnerFunction(FunctionDefinition node) {}
 }