Fix null dereference after OOM.

test/cctest/test-debug.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 7514 matching lines @@
 
 TEST(LiveEditDisabled) {
   v8::internal::FLAG_allow_natives_syntax = true;
   v8::HandleScope scope;
   LocalContext context;
   v8::Debug::SetLiveEditEnabled(false);
   CompileRun("%LiveEditCompareStrings('', '')");
 }
 
 
+TEST(DebugContextOOM) {
+  v8::HandleScope scope;
+  LocalContext context;
+  v8::V8::IgnoreOutOfMemoryException();
+
+  v8::Local<v8::Value> result = CompileRun("a = '1'; while (true) a += a;");
+
+  // Check for out of memory state.
+  CHECK(result.IsEmpty());
+  CHECK(context->HasOutOfMemoryException());
+
+  v8::Debug::GetDebugContext();
+}
+
 #endif  // ENABLE_DEBUGGER_SUPPORT