lazy instantiation of the default isolate

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 5012 matching lines @@
     ArrayBuffer::Allocator* allocator) {
   if (!ApiCheck(i::V8::ArrayBufferAllocator() == NULL,
                 "v8::V8::SetArrayBufferAllocator",
                 "ArrayBufferAllocator might only be set once"))
     return;
   i::V8::SetArrayBufferAllocator(allocator);
 }
 
 
 bool v8::V8::Dispose() {
-  i::Isolate* isolate = i::Isolate::Current();
-  if (!ApiCheck(isolate != NULL && isolate->IsDefaultIsolate(),
+  i::Isolate* isolate = i::Isolate::UncheckedCurrent();
+  if (!ApiCheck(isolate == NULL || isolate->IsDefaultIsolate(),
                 "v8::V8::Dispose()",
                 "Use v8::Isolate::Dispose() for a non-default isolate.")) {
     return false;
   }
-  i::V8::TearDown();
-  return true;
+  return i::V8::TearDown();
 }
 
 
 HeapStatistics::HeapStatistics(): total_heap_size_(0),
                                   total_heap_size_executable_(0),
                                   total_physical_size_(0),
                                   used_heap_size_(0),
                                   heap_size_limit_(0) { }
 
 
@@ skipping 2524 matching lines @@
   Isolate* isolate = reinterpret_cast<Isolate*>(info.GetIsolate());
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 } }  // namespace v8::internal