Don't unload debug context after it was requested through public API

test/cctest/test-debug.cc

Index: test/cctest/test-debug.cc
===================================================================
--- test/cctest/test-debug.cc	(revision 4517)
+++ test/cctest/test-debug.cc	(working copy)
@@ -6139,3 +6139,12 @@
   debugger_context = v8::Handle<v8::Context>();
   CheckDebuggerUnloaded();
 }
+
+
+TEST(DebugContextIsPreservedBetweenAccesses) {
+  v8::HandleScope scope;
+  v8::Local<v8::Context> context1 = v8::Debug::GetDebugContext();
+  v8::Local<v8::Context> context2 = v8::Debug::GetDebugContext();
+  CHECK_EQ(*context1, *context2);
+}
+