dart2js cps: Compile some loops as 'for' loops.

pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart

Index: pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart
diff --git a/pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart b/pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart
index d82377a63ba7c085ed9625a37717f2606d235b97..0b94b050ab250f3d2f9e5806b31e58025a58f501 100644
--- a/pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart
+++ b/pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart
@@ -300,8 +300,10 @@ class TreeTracer extends TracerUtil with StatementVisitor {
   visitWhileCondition(WhileCondition node) {
     String bodyTarget = collector.substatements[node.body].name;
     String nextTarget = collector.substatements[node.next].name;
+    String updates = node.updates.map(expr).join(', ');
     printStatement(null, "while ${expr(node.condition)}");
     printStatement(null, "do $bodyTarget");
+    printStatement(null, "updates ($updates)");
     printStatement(null, "then $nextTarget" );
   }