Ensure v8 is initialized before initializing debug context

test/cctest/test-debug.cc

Index: test/cctest/test-debug.cc
===================================================================
--- test/cctest/test-debug.cc	(revision 4528)
+++ test/cctest/test-debug.cc	(working copy)
@@ -6147,3 +6147,12 @@
 }
 
 
+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);
+  // Make sure debugger is unloaded before running other tests.
+  v8::internal::ForceUnloadDebugger();
+  CheckDebuggerUnloaded();
+}