Track whether a node or variable are likely to be a Smi value. Propagate that...

src/ast.h

Index: src/ast.h
===================================================================
--- src/ast.h	(revision 629)
+++ src/ast.h	(working copy)
@@ -150,6 +150,12 @@
   // statement. This is used to transform postfix increments to
   // (faster) prefix increments.
   virtual void MarkAsStatement() { /* do nothing */ }
+
+  // Static type information for this expression.
+  StaticType* type() { return &type_; }
+
+ private:
+  StaticType type_;
 };