Fix incorrect desugaring of cascades.

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
diff --git a/runtime/vm/parser.cc b/runtime/vm/parser.cc
index 179d96d8fc0743e37cf0aedf8081b1bfcfea0b93..d83d7746e84bfa174597e4c47dcea5eddf872f42 100644
--- a/runtime/vm/parser.cc
+++ b/runtime/vm/parser.cc
@@ -6912,9 +6912,10 @@ AstNode* Parser::ParseCascades(AstNode* expr) {
   intptr_t cascade_pos = TokenPos();
   LocalVariable* cascade_receiver_var =
       CreateTempConstVariable(cascade_pos, "casc");
+  SequenceNode* cascade = new SequenceNode(cascade_pos, NULL);

[Ivan Posva, 2013/01/04 17:31:56]

Can you please explain why this is not a hack? You make it sound as if the
LoadLocal can overtake the StoreLocal here in general, which makes me nervous.

Adding a comment to the creation of the SequenceNode would help, thanks.

[Kevin Millikin (Google), 2013/01/07 09:14:14]

I think it is a hack.  I'll add a comment here, at the other use, and in the
LoadLocal AST class explaining it.

   StoreLocalNode* save_cascade =
       new StoreLocalNode(cascade_pos, cascade_receiver_var, expr);
-  current_block_->statements->Add(save_cascade);
+  cascade->Add(save_cascade);
   while (CurrentToken() == Token::kCASCADE) {
     cascade_pos = TokenPos();
     LoadLocalNode* load_cascade_receiver =
@@ -6952,10 +6953,10 @@ AstNode* Parser::ParseCascades(AstNode* expr) {
       }
       expr = assign_expr;
     }
-    current_block_->statements->Add(expr);
+    cascade->Add(expr);
   }
   // Result of the cascade is the receiver.
-  return new LoadLocalNode(cascade_pos, cascade_receiver_var);
+  return new LoadLocalNode(cascade_pos, cascade_receiver_var, cascade);
 }