Fix from Paul Lind that helps post-isolates V8 work with older

src/api.cc

 // 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 3987 matching lines @@
   heap_statistics->set_total_heap_size_executable(
       heap->CommittedMemoryExecutable());
   heap_statistics->set_used_heap_size(heap->SizeOfObjects());
   heap_statistics->set_heap_size_limit(heap->MaxReserved());
 }
 
 
 bool v8::V8::IdleNotification() {
   // Returning true tells the caller that it need not
   // continue to call IdleNotification.
-  if (!i::Isolate::Current()->IsInitialized()) return true;
+  i::Isolate* isolate = i::Isolate::Current();
+  if (isolate == NULL || !isolate->IsInitialized()) return true;
   return i::V8::IdleNotification();
 }
 
 
 void v8::V8::LowMemoryNotification() {
   i::Isolate* isolate = i::Isolate::Current();
-  if (!isolate->IsInitialized()) return;
+  if (isolate == NULL || !isolate->IsInitialized()) return;
   isolate->heap()->CollectAllAvailableGarbage();
 }
 
 
 int v8::V8::ContextDisposedNotification() {
   i::Isolate* isolate = i::Isolate::Current();
   if (!isolate->IsInitialized()) return 0;
   return isolate->heap()->NotifyContextDisposed();
 }
 
@@ skipping 2071 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