Initialize the async jump variable with a smi to avoid polymorphic comparison.

runtime/vm/ast_transformer.cc

Index: runtime/vm/ast_transformer.cc
===================================================================
--- runtime/vm/ast_transformer.cc	(revision 41096)
+++ runtime/vm/ast_transformer.cc	(working copy)
@@ -142,8 +142,6 @@
   AwaitMarkerNode* await_marker = new (I) AwaitMarkerNode(
       AwaitMarkerNode::kNewContinuationState);
   await_marker->set_scope(is_future_scope);
-  GetVariableInScope(is_future_scope, Symbols::AwaitJumpVar());

[hausner, 2014/10/14 16:29:55]

I am not sure why the lookup of these variables is here. But this lookup was
introduced by this CL

https://codereview.chromium.org//520223002

That fixed scope-related issues. Looking up the variable in this scope rather
than the top-level scope of the closure (as your change does) may have a subtle
desired side effect.

[Florian Schneider, 2014/10/15 11:40:59]

Here the side effect occurs twice (here and again when looking up the same
variables in the EffectGraphVisitr::VisitAwaitMarkerNode). Maybe the code
changed so that this became redundant.

-  GetVariableInScope(is_future_scope, Symbols::AwaitContextVar());
   is_future_branch->Add(await_marker);
   ArgumentListNode* args = new(I) ArgumentListNode(Scanner::kNoSourcePos);
   args->Add(new(I) LoadLocalNode(Scanner::kNoSourcePos, async_op));
@@ -279,8 +277,7 @@
 
 
 void AwaitTransformer::VisitBinaryOpNode(BinaryOpNode* node) {
-  node->left()->Visit(this);
-  AstNode* new_left = result_;
+  AstNode* new_left = Transform(node->left());
   AstNode* new_right = NULL;
   // Preserve lazy evaluaton.
   if ((node->kind() == Token::kAND) || (node->kind() == Token::kOR)) {
@@ -299,15 +296,9 @@
 
 void AwaitTransformer::VisitBinaryOpWithMask32Node(
     BinaryOpWithMask32Node* node) {
-  node->left()->Visit(this);
-  AstNode* new_left = result_;
-  AstNode* new_right = NULL;
-  // Preserve lazy evaluaton.
-  if ((node->kind() == Token::kAND) || (node->kind() == Token::kOR)) {
-    new_right = LazyTransform(node->kind(), new_left, node->right());
-  } else {
-    new_right = Transform(node->right());
-  }
+  ASSERT((node->kind() != Token::kAND) && (node->kind() != Token::kOR));
+  AstNode* new_left = Transform(node->left());
+  AstNode* new_right = Transform(node->right());
   LocalVariable* result = AddToPreambleNewTempVar(
       new(I) BinaryOpWithMask32Node(node->token_pos(),
                                     node->kind(),