Deprecate Promise::Chain from V8 APIs

The Promise::Chain logic is moved to a helper function to avoid
a violation of deprecated function usage.

R=rossberg,jochen
BUG=v8:3237
LOG=Y

Review URL: https://codereview.chromium.org/1477023002

Cr-Commit-Position: refs/heads/master@{#32670}

include/v8.h

@@ -3349,10 +3349,11 @@ class V8_EXPORT Promise : public Object {
    * an argument. If the promise is already resolved/rejected, the handler is
    * invoked at the end of turn.
    */
-  V8_DEPRECATE_SOON("Use maybe version",
+  V8_DEPRECATE_SOON("Use maybe version of Then",
                     Local<Promise> Chain(Local<Function> handler));
-  V8_WARN_UNUSED_RESULT MaybeLocal<Promise> Chain(Local<Context> context,
-                                                  Local<Function> handler);
+  V8_DEPRECATE_SOON("Use Then",
+                    V8_WARN_UNUSED_RESULT MaybeLocal<Promise> Chain(
+                        Local<Context> context, Local<Function> handler));
 
   V8_DEPRECATE_SOON("Use maybe version",
                     Local<Promise> Catch(Local<Function> handler));

src/api.cc

@@ -6461,10 +6461,12 @@ void Promise::Resolver::Reject(Local<Value> value) {
 }
 
 
-MaybeLocal<Promise> Promise::Chain(Local<Context> context,
-                                   Local<Function> handler) {
+namespace {
+
+MaybeLocal<Promise> DoChain(Value* value, Local<Context> context,
+                            Local<Function> handler) {
   PREPARE_FOR_EXECUTION(context, "Promise::Chain", Promise);
-  auto self = Utils::OpenHandle(this);
+  auto self = Utils::OpenHandle(value);
   i::Handle<i::Object> argv[] = {Utils::OpenHandle(*handler)};
   i::Handle<i::Object> result;
   has_pending_exception = !i::Execution::Call(isolate, isolate->promise_chain(),
@@ -6474,10 +6476,18 @@ MaybeLocal<Promise> Promise::Chain(Local<Context> context,
   RETURN_ESCAPED(Local<Promise>::Cast(Utils::ToLocal(result)));
 }
 
+}  // namespace
+
+
+MaybeLocal<Promise> Promise::Chain(Local<Context> context,
+                                   Local<Function> handler) {
+  return DoChain(this, context, handler);
+}
+
 
 Local<Promise> Promise::Chain(Local<Function> handler) {
   auto context = ContextFromHeapObject(Utils::OpenHandle(this));
-  RETURN_TO_LOCAL_UNCHECKED(Chain(context, handler), Promise);
+  RETURN_TO_LOCAL_UNCHECKED(DoChain(this, context, handler), Promise);
 }