X87: [turbofan] Introduce JSCallForwardVarargs operator.

src/x87/interface-descriptors-x87.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.
 
 #if V8_TARGET_ARCH_X87
 
 #include "src/interface-descriptors.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 156 matching lines @@
 
 
 void CallTrampolineDescriptor::InitializePlatformSpecific(
     CallInterfaceDescriptorData* data) {
   // eax : number of arguments
   // edi : the target to call
   Register registers[] = {edi, eax};
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
 
+void CallForwardVarargsDescriptor::InitializePlatformSpecific(
+    CallInterfaceDescriptorData* data) {
+  // ecx : start index (to support rest parameters)
+  // edi : the target to call
+  Register registers[] = {edi, ecx};
+  data->InitializePlatformSpecific(arraysize(registers), registers);
+}
 
 void ConstructStubDescriptor::InitializePlatformSpecific(
     CallInterfaceDescriptorData* data) {
   // eax : number of arguments
   // edx : the new target
   // edi : the target to call
   // ebx : allocation site or undefined
   Register registers[] = {edi, edx, eax, ebx};
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
@@ skipping 218 matching lines @@
       ebx,  // the JSGeneratorObject to resume
       edx   // the resume mode (tagged)
   };
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X87