[debug] Revert debug API removal

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 6ab8c72d8c05fa530d7f1c86fe6b3c3d5c17f112..b8210986f6a00540fcd3c4d20e3b966e268f93ec 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -8734,7 +8734,9 @@ bool Debug::CheckDebugBreak(Isolate* isolate) {
 
 void Debug::SetMessageHandler(Isolate* isolate,
                               v8::Debug::MessageHandler handler) {
-  UNIMPLEMENTED();
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  ENTER_V8(i_isolate);
+  i_isolate->debug()->SetMessageHandler(handler);
 }
 
 
@@ -8742,7 +8744,9 @@ void Debug::SendCommand(Isolate* isolate,
                         const uint16_t* command,
                         int length,
                         ClientData* client_data) {
-  UNIMPLEMENTED();
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  internal_isolate->debug()->EnqueueCommandMessage(
+      i::Vector<const uint16_t>(command, length), client_data);
 }
 
 
@@ -8767,11 +8771,28 @@ MaybeLocal<Value> Debug::Call(Local<Context> context,
 
 MaybeLocal<Value> Debug::GetMirror(Local<Context> context,
                                    v8::Local<v8::Value> obj) {
-  UNIMPLEMENTED();
-  return MaybeLocal<Value>();
+  PREPARE_FOR_EXECUTION(context, Debug, GetMirror, Value);
+  i::Debug* isolate_debug = isolate->debug();
+  has_pending_exception = !isolate_debug->Load();
+  RETURN_ON_FAILED_EXECUTION(Value);
+  i::Handle<i::JSObject> debug(isolate_debug->debug_context()->global_object());
+  auto name = isolate->factory()->NewStringFromStaticChars("MakeMirror");
+  auto fun_obj = i::JSReceiver::GetProperty(debug, name).ToHandleChecked();
+  auto v8_fun = Utils::CallableToLocal(i::Handle<i::JSFunction>::cast(fun_obj));
+  const int kArgc = 1;
+  v8::Local<v8::Value> argv[kArgc] = {obj};
+  Local<Value> result;
+  has_pending_exception =
+      !v8_fun->Call(context, Utils::ToLocal(debug), kArgc, argv)
+           .ToLocal(&result);
+  RETURN_ON_FAILED_EXECUTION(Value);
+  RETURN_ESCAPED(result);
+}
+
+void Debug::ProcessDebugMessages(Isolate* isolate) {
+  reinterpret_cast<i::Isolate*>(isolate)->debug()->ProcessDebugMessages(true);
 }
 
-void Debug::ProcessDebugMessages(Isolate* isolate) { UNIMPLEMENTED(); }
 
 Local<Context> Debug::GetDebugContext(Isolate* isolate) {
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
@@ -8781,8 +8802,12 @@ Local<Context> Debug::GetDebugContext(Isolate* isolate) {
 
 
 MaybeLocal<Context> Debug::GetDebuggedContext(Isolate* isolate) {
-  UNIMPLEMENTED();
-  return MaybeLocal<Context>();
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  ENTER_V8(i_isolate);
+  if (!i_isolate->debug()->in_debug_scope()) return MaybeLocal<Context>();
+  i::Handle<i::Object> calling = i_isolate->GetCallingNativeContext();
+  if (calling.is_null()) return MaybeLocal<Context>();
+  return Utils::ToLocal(i::Handle<i::Context>::cast(calling));
 }
 
 void Debug::SetLiveEditEnabled(Isolate* isolate, bool enable) {