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

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

 library tree_ir.integrity;
 
 import 'tree_ir_nodes.dart';
 
 /// Performs integrity checks on the tree_ir.
 ///
 /// Should only be run for debugging purposes, not in production.
 ///
 /// - Reference counts on must match the actual number of references.
 /// - Labels must be in scope when referenced.
@@ skipping 84 matching lines @@
 
   visitLabeledStatement(LabeledStatement node) {
     visitJumpTargetBody(node);
     visitStatement(node.next);
   }
 
   visitWhileTrue(WhileTrue node) {
     visitJumpTargetBody(node);
   }
 
-  visitWhileCondition(WhileCondition node) {
+  visitFor(For node) {
     visitExpression(node.condition);
     visitJumpTargetBody(node);
+    node.updates.forEach(visitExpression);
     visitStatement(node.next);
   }
 
   visitBreak(Break node) {
     if (!label2declaration.containsKey(node.target)) {
       error('Break to label that is not in scope');
     }
     if (label2declaration[node.target] is! LabeledStatement) {
       error('Break to non-labeled statement ${label2declaration[node.target]}');
     }
@@ skipping 38 matching lines @@
       if (reads != variable.readCount || writes != variable.writeCount) {
         error('Invalid reference count for $variable:\n'
               '- Variable has $reads reads and $writes writes\n'
               '- Reference count is ${variable.readCount} reads and '
               '${variable.writeCount} writes');
       }
     }
   }
 
 }