ES6 symbols: fix corner cases of equality operators

src/objects-inl.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 2486 matching lines @@
 void Name::set_hash_field(uint32_t value) {
   WRITE_UINT32_FIELD(this, kHashFieldOffset, value);
 #if V8_HOST_ARCH_64_BIT
   WRITE_UINT32_FIELD(this, kHashFieldOffset + kIntSize, 0);
 #endif
 }
 
 
 bool Name::Equals(Name* other) {
   if (other == this) return true;
-  if (this->IsUniqueName() && other->IsUniqueName()) return false;
+  if (this->IsSymbol() || other->IsSymbol() ||
+      (this->IsInternalizedString() && other->IsInternalizedString())) {
+    return false;
+  }
   return String::cast(this)->SlowEquals(String::cast(other));
 }
 
 
 ACCESSORS(Symbol, name, Object, kNameOffset)
 
 
 bool String::Equals(String* other) {
   if (other == this) return true;
   if (this->IsInternalizedString() && other->IsInternalizedString()) {
@@ skipping 3504 matching lines @@
 #undef WRITE_UINT32_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_