build fix for 17049

src/isolate.cc

 // 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 372 matching lines @@
 }
 
 
 void Isolate::SetCrashIfDefaultIsolateInitialized() {
   LockGuard<Mutex> lock_guard(&process_wide_mutex_);
   CHECK(default_isolate_status_ != kDefaultIsolateInitialized);
   default_isolate_status_ = kDefaultIsolateCrashIfInitialized;
 }
 
 
-Isolate* Isolate::EnsureDefaultIsolate() {
+Isolate* Isolate::EnsureDefaultIsolate(bool must_be_null) {
   static Isolate* default_isolate_ = NULL;
   LockGuard<Mutex> lock_guard(&process_wide_mutex_);
   CHECK(default_isolate_status_ != kDefaultIsolateCrashIfInitialized);
+  if (must_be_null) {
+    CHECK(default_isolate_ == NULL);
+  }
   if (default_isolate_ == NULL) {
     default_isolate_ = new Isolate(true);
   }
   // Can't use SetIsolateThreadLocals(default_isolate_, NULL) here
   // because a non-null thread data may be already set.
   if (Thread::GetThreadLocal(isolate_key_) == NULL) {
     Thread::SetThreadLocal(isolate_key_, default_isolate_);
   }
 
   return default_isolate_;
@@ skipping 2124 matching lines @@
 
 #ifdef DEBUG
 #define ISOLATE_FIELD_OFFSET(type, name, ignored)                       \
 const intptr_t Isolate::name##_debug_offset_ = OFFSET_OF(Isolate, name##_);
 ISOLATE_INIT_LIST(ISOLATE_FIELD_OFFSET)
 ISOLATE_INIT_ARRAY_LIST(ISOLATE_FIELD_OFFSET)
 #undef ISOLATE_FIELD_OFFSET
 #endif
 
 } }  // namespace v8::internal