Fix and re-enable test-api/InitializeAndDispose.

src/api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 395 matching lines @@
 }
 
 
 void RegisteredExtension::UnregisterAll() {
   RegisteredExtension* re = first_extension_;
   while (re != NULL) {
     RegisteredExtension* next = re->next();
     delete re;
     re = next;
   }
+  first_extension_ = NULL;
 }
 
 
 void RegisterExtension(Extension* that) {
   RegisteredExtension* extension = new RegisteredExtension(that);
   RegisteredExtension::Register(extension);
 }
 
 
 Extension::Extension(const char* name,
@@ skipping 7251 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