Include what you use for allocation, api, assembler, and ast.

src/type-info.h

Index: src/type-info.h
diff --git a/src/type-info.h b/src/type-info.h
index 9d3080abbff3ca529687a1aeda922fd56efbd4c2..80ebf0c63a887ff2b15b94730feb64ee8d56a33c 100644
--- a/src/type-info.h
+++ b/src/type-info.h
@@ -1,4 +1,4 @@
-// Copyright 2011 the V8 project authors. All rights reserved.
+// Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
@@ -223,6 +223,7 @@ class CaseClause;
 class CompareOperation;
 class CompilationInfo;
 class CountOperation;
+class Expression;
 class Property;
 class SmallMapList;
 class UnaryOperation;