Better codegen for '<expression> === void <literal>'.

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index c2339e3fc74f338e8b754467ebc2fc589ccc7beb..b0d3756c4148e7aa35f9ea4265ddafb0c6e24683 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -881,6 +881,11 @@ class HGraphBuilder: public AstVisitor {
                                   HValue* receiver,
                                   ZoneMapList* types,
                                   Handle<String> name);
+  void HandleLiteralCompareTypeof(CompareOperation* compare_expr,
+                                  Expression* expr,
+                                  Handle<String> check);
+  void HandleLiteralCompareUndefined(CompareOperation* compare_expr,
+                                     Expression* expr);                                  
 
   HCompareSymbolEq* BuildSymbolCompare(HValue* left,
                                        HValue* right,