Add an IC for CompareNil operations

src/ast.h

 // 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:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 321 matching lines @@
 
   // True iff the expression is a literal represented as a smi.
   bool IsSmiLiteral();
 
   // True iff the expression is a string literal.
   bool IsStringLiteral();
 
   // True iff the expression is the null literal.
   bool IsNullLiteral();
 
+  // True iff the expression is the null literal.
+  bool IsUndefinedLiteral();
+
   // Type feedback information for assignments and properties.
   virtual bool IsMonomorphic() {
     UNREACHABLE();
     return false;
   }
   virtual SmallMapList* GetReceiverTypes() {
     UNREACHABLE();
     return NULL;
   }
   Handle<Map> GetMonomorphicReceiverType() {
@@ skipping 2671 matching lines @@
  private:
   Isolate* isolate_;
   Zone* zone_;
   Visitor visitor_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_AST_H_