dart2js cps: Remove dart2dart from cps pipeline and clean up.

pkg/compiler/lib/src/tree_ir/optimization/loop_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.
 
-part of tree_ir.optimization;
+library tree_ir.optimization.loop_rewriter;
+
+import 'optimization.dart' show Pass;
+import '../tree_ir_nodes.dart';
 
 /// Rewrites [WhileTrue] statements.
 ///
 /// Before this phase, loops usually contain a lot of "exit code", that is,
 /// code that happens at a point where a [Continue] can no longer be reached,
 /// and is therefore not really part of the loop.
 /// Exit code is moved down after the loop using the following rewrites rules:
 ///
 /// EXTRACT LABELED STATEMENT:
 ///
@@ skipping 34 matching lines @@
 /// Note that the last pattern above needs no iteration since nested ifs
 /// have been collapsed previously in the [StatementRewriter] phase.
 ///
 /// [WhileCondition] statements exist only after this phase.
 class LoopRewriter extends RecursiveTransformer
                    implements Pass {
   String get passName => 'Loop rewriter';
 
   Set<Label> usedContinueLabels = new Set<Label>();
 
-  void rewrite(RootNode root) {
-    root.replaceEachBody(visitStatement);
+  void rewrite(FunctionDefinition root) {
+    root.body = visitStatement(root.body);
   }
 
   @override
   void visitInnerFunction(FunctionDefinition node) {
     node.body = new LoopRewriter().visitStatement(node.body);
   }
 
   Statement visitContinue(Continue node) {
     usedContinueLabels.add(node.target);
     return node;
@@ skipping 52 matching lines @@
     } else {
       node.body = visitStatement(node.body);
       usedContinueLabels.remove(node.label);
     }
 
     if (head == null) return loop;
     tail.body = loop;
     return head;
   }
 }