[es6] Initial steps towards a correct implementation of IsCallable.

src/api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 4246 matching lines @@
                                       Value);
   i::TimerEventScope<i::TimerEventExecute> timer_scope(isolate);
   auto self = Utils::OpenHandle(this);
   auto recv_obj = Utils::OpenHandle(*recv);
   STATIC_ASSERT(sizeof(v8::Local<v8::Value>) == sizeof(i::Object**));
   i::Handle<i::Object>* args = reinterpret_cast<i::Handle<i::Object>*>(argv);
   i::Handle<i::JSFunction> fun;
   if (self->IsJSFunction()) {
     fun = i::Handle<i::JSFunction>::cast(self);
   } else {
-    i::Handle<i::Object> delegate;
-    has_pending_exception = !i::Execution::TryGetFunctionDelegate(isolate, self)
-                                 .ToHandle(&delegate);
+    has_pending_exception =
+        !i::Execution::GetFunctionDelegate(isolate, self).ToHandle(&fun);
     RETURN_ON_FAILED_EXECUTION(Value);
-    fun = i::Handle<i::JSFunction>::cast(delegate);
     recv_obj = self;
   }
   Local<Value> result;
   has_pending_exception =
       !ToLocal<Value>(
           i::Execution::Call(isolate, fun, recv_obj, argc, args, true),
           &result);
   RETURN_ON_FAILED_EXECUTION(Value);
   RETURN_ESCAPED(result);
 }
@@ skipping 17 matching lines @@
   STATIC_ASSERT(sizeof(v8::Local<v8::Value>) == sizeof(i::Object**));
   i::Handle<i::Object>* args = reinterpret_cast<i::Handle<i::Object>*>(argv);
   if (self->IsJSFunction()) {
     auto fun = i::Handle<i::JSFunction>::cast(self);
     Local<Value> result;
     has_pending_exception =
         !ToLocal<Value>(i::Execution::New(fun, argc, args), &result);
     RETURN_ON_FAILED_EXECUTION(Value);
     RETURN_ESCAPED(result);
   }
-  i::Handle<i::Object> delegate;
-  has_pending_exception = !i::Execution::TryGetConstructorDelegate(
-                               isolate, self).ToHandle(&delegate);
+  i::Handle<i::JSFunction> fun;
+  has_pending_exception =
+      !i::Execution::GetConstructorDelegate(isolate, self).ToHandle(&fun);
   RETURN_ON_FAILED_EXECUTION(Value);
-  if (!delegate->IsUndefined()) {
-    auto fun = i::Handle<i::JSFunction>::cast(delegate);
-    Local<Value> result;
-    has_pending_exception =
-        !ToLocal<Value>(i::Execution::Call(isolate, fun, self, argc, args),
-                        &result);
-    RETURN_ON_FAILED_EXECUTION(Value);
-    DCHECK(!delegate->IsUndefined());
-    RETURN_ESCAPED(result);
-  }
-  return MaybeLocal<Value>();
+  Local<Value> result;
+  has_pending_exception = !ToLocal<Value>(
+      i::Execution::Call(isolate, fun, self, argc, args), &result);
+  RETURN_ON_FAILED_EXECUTION(Value);
+  RETURN_ESCAPED(result);
 }
 
 
 Local<v8::Value> Object::CallAsConstructor(int argc,
                                            v8::Local<v8::Value> argv[]) {
   auto context = ContextFromHeapObject(Utils::OpenHandle(this));
   Local<Value>* argv_cast = reinterpret_cast<Local<Value>*>(argv);
   RETURN_TO_LOCAL_UNCHECKED(CallAsConstructor(context, argc, argv_cast), Value);
 }
 
@@ skipping 4079 matching lines @@
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 }  // namespace internal
 }  // namespace v8