Unify the handling of comparinsons against null and undefined.

src/token.h

 // Copyright 2011 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 198 matching lines @@
   }
 
   static bool IsCompareOp(Value op) {
     return EQ <= op && op <= IN;
   }
 
   static bool IsOrderedCompareOp(Value op) {
     return op == LT || op == LTE || op == GT || op == GTE;
   }
 
+  static bool IsEqualityOp(Value op) {
+    return op == EQ || op == EQ_STRICT;
+  }
+
   static Value NegateCompareOp(Value op) {
     ASSERT(IsCompareOp(op));
     switch (op) {
       case EQ: return NE;
       case NE: return EQ;
       case EQ_STRICT: return NE_STRICT;
       case LT: return GTE;
       case GT: return LTE;
       case LTE: return GT;
       case GTE: return LT;
@@ skipping 51 matching lines @@
  private:
   static const char* const name_[NUM_TOKENS];
   static const char* const string_[NUM_TOKENS];
   static const int8_t precedence_[NUM_TOKENS];
   static const char token_type[NUM_TOKENS];
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_TOKEN_H_