Some optimizations for packer.js.

src/objects.h

 // Copyright 2006-2009 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 2170 matching lines @@
   // added.  The return value is the symbol table which might have
   // been enlarged.  If the return value is not a failure, the symbol
   // pointer *s is set to the symbol found.
   Object* LookupSymbol(Vector<const char> str, Object** s);
   Object* LookupString(String* key, Object** s);
 
   // Looks up a symbol that is equal to the given string and returns
   // true if it is found, assigning the symbol to the given output
   // parameter.
   bool LookupSymbolIfExists(String* str, String** symbol);
+  bool LookupTwoCharsIfExists(uint32_t c1, uint32_t c2, String** symbol);
 
   // Casting.
   static inline SymbolTable* cast(Object* obj);
 
  private:
   Object* LookupKey(HashTableKey* key, Object** s);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(SymbolTable);
 };
 
@@ skipping 1638 matching lines @@
   }
 
   inline uint32_t GetHash();
 
   int length_;
   uint32_t raw_running_hash_;
   uint32_t array_index_;
   bool is_array_index_;
   bool is_first_char_;
   bool is_valid_;
+  friend class TwoCharHashTableKey;
 };
 
 
 // The characteristics of a string are stored in its map.  Retrieving these
 // few bits of information is moderately expensive, involving two memory
 // loads where the second is dependent on the first.  To improve efficiency
 // the shape of the string is given its own class so that it can be retrieved
 // once and used for several string operations.  A StringShape is small enough
 // to be passed by value and is immutable, but be aware that flattening a
 // string can potentially alter its shape.  Also be aware that a GC caused by
@@ skipping 1192 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_