Revert of [debugger] deprecate v8::Debug:GetDebugContext.

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 5645 matching lines @@
   foo->Call(debugee_context, env->Global(), 0, NULL).ToLocalChecked();
   CHECK_EQ(1, break_point_hit_count);
 
   v8::Debug::SetDebugEventListener(isolate, nullptr);
   debugee_context = v8::Local<v8::Context>();
   debugger_context = v8::Local<v8::Context>();
   CheckDebuggerUnloaded(isolate);
 }
 
 
+TEST(DebugContextIsPreservedBetweenAccesses) {
+  v8::HandleScope scope(CcTest::isolate());
+  v8::Debug::SetDebugEventListener(CcTest::isolate(),
+                                   DebugEventBreakPointHitCount);
+  v8::Local<v8::Context> context1 =
+      v8::Debug::GetDebugContext(CcTest::isolate());
+  v8::Local<v8::Context> context2 =
+      v8::Debug::GetDebugContext(CcTest::isolate());
+  CHECK(v8::Utils::OpenHandle(*context1).is_identical_to(
+            v8::Utils::OpenHandle(*context2)));
+  v8::Debug::SetDebugEventListener(CcTest::isolate(), nullptr);
+}
+
+
+TEST(NoDebugContextWhenDebuggerDisabled) {
+  v8::HandleScope scope(CcTest::isolate());
+  v8::Local<v8::Context> context =
+      v8::Debug::GetDebugContext(CcTest::isolate());
+  CHECK(context.IsEmpty());
+}
+
 static v8::Local<v8::Value> expected_callback_data;
 static void DebugEventContextChecker(const v8::Debug::EventDetails& details) {
   CHECK(details.GetEventContext() == expected_context);
   CHECK(expected_callback_data->Equals(details.GetEventContext(),
                                        details.GetCallbackData())
             .FromJust());
 }
 
 
 // Check that event details contain context where debug event occured.
@@ skipping 961 matching lines @@
       "function foo() {\n"
       "  try { throw new Error(); } catch (e) {}\n"
       "}\n"
       "debugger;\n"
       "foo();\n"
       "foo();\n");
 
   v8::Debug::SetDebugEventListener(env->GetIsolate(), nullptr);
   CHECK_EQ(break_point_hit_count, 4);
 }