V8 API: Add a missing NULL check into Isolate::GetCurrentContext().

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 9b1d01cd8f4ead1bab6e46f03c3ed362157f8c13..5cf43f4a551dd6ca46c955eb8b7953abfaee0ac7 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -6538,10 +6538,11 @@ CpuProfiler* Isolate::GetCpuProfiler() {
 
 v8::Local<v8::Context> Isolate::GetCurrentContext() {
   i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(this);
-  i::Handle<i::Object> current = internal_isolate->native_context();
-  if (current.is_null()) return Local<Context>();
-  i::Handle<i::Context> context = i::Handle<i::Context>::cast(current);
-  return Utils::ToLocal(context);
+  i::Context* context = internal_isolate->context();
+  if (context == NULL) return Local<Context>();
+  i::Context* native_context = context->global_object()->native_context();
+  if (native_context == NULL) return Local<Context>();
+  return Utils::ToLocal(i::Handle<i::Context>(native_context));
 }