[runtime] Introduce dedicated JSBoundFunction to represent bound functions.

src/runtime/runtime-object.cc

 // Copyright 2014 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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/isolate-inl.h"
@@ skipping 1328 matching lines @@
   // {callable} must have a [[Call]] internal method.
   if (!callable->IsCallable()) {
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate,
         NewTypeError(MessageTemplate::kInstanceofFunctionExpected, callable));
   }
   // If {object} is not a receiver, return false.
   if (!object->IsJSReceiver()) {
     return isolate->heap()->false_value();
   }
-  // Check if {callable} is bound, if so, get [[BoundFunction]] from it and use
-  // that instead of {callable}.
-  if (callable->IsJSFunction()) {
-    Handle<JSFunction> function = Handle<JSFunction>::cast(callable);
-    if (function->shared()->bound()) {
-      Handle<BindingsArray> bindings(function->function_bindings(), isolate);
-      callable = handle(bindings->bound_function(), isolate);
-    }
+  // Check if {callable} is bound, if so, get [[BoundTargetFunction]] from it
+  // and use that instead of {callable}.
+  while (callable->IsJSBoundFunction()) {
+    callable =
+        handle(Handle<JSBoundFunction>::cast(callable)->bound_target_function(),
+               isolate);
   }
   DCHECK(callable->IsCallable());
   // Get the "prototype" of {callable}; raise an error if it's not a receiver.
   Handle<Object> prototype;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       isolate, prototype,
       Object::GetProperty(callable, isolate->factory()->prototype_string()));
   if (!prototype->IsJSReceiver()) {
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate,
@@ skipping 47 matching lines @@
 
 RUNTIME_FUNCTION(Runtime_ObjectDefineProperties) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 2);
   CONVERT_ARG_HANDLE_CHECKED(Object, o, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, properties, 1);
   return JSReceiver::DefineProperties(isolate, o, properties);
 }
 }  // namespace internal
 }  // namespace v8