Ensure default isolate is present in Add/RemoveCallCompletedCallback.

src/api.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 5261 matching lines @@
 void V8::RemoveMemoryAllocationCallback(MemoryAllocationCallback callback) {
   i::Isolate* isolate = i::Isolate::Current();
   if (IsDeadCheck(isolate, "v8::V8::RemoveMemoryAllocationCallback()")) return;
   isolate->memory_allocator()->RemoveMemoryAllocationCallback(
       callback);
 }
 
 
 void V8::AddCallCompletedCallback(CallCompletedCallback callback) {
   if (callback == NULL) return;
+  i::Isolate::EnsureDefaultIsolate();
   i::Isolate* isolate = i::Isolate::Current();
   if (IsDeadCheck(isolate, "v8::V8::AddLeaveScriptCallback()")) return;
   i::V8::AddCallCompletedCallback(callback);
 }
 
 
 void V8::RemoveCallCompletedCallback(CallCompletedCallback callback) {
+  i::Isolate::EnsureDefaultIsolate();
   i::Isolate* isolate = i::Isolate::Current();
   if (IsDeadCheck(isolate, "v8::V8::RemoveLeaveScriptCallback()")) return;
   i::V8::RemoveCallCompletedCallback(callback);
 }
 
 
 void V8::PauseProfiler() {
   i::Isolate* isolate = i::Isolate::Current();
   isolate->logger()->PauseProfiler();
 }
@@ skipping 1077 matching lines @@
 
 
 char* HandleScopeImplementer::Iterate(ObjectVisitor* v, char* storage) {
   HandleScopeImplementer* scope_implementer =
       reinterpret_cast<HandleScopeImplementer*>(storage);
   scope_implementer->IterateThis(v);
   return storage + ArchiveSpacePerThread();
 }
 
 } }  // namespace v8::internal