[turbofan] Introduce JSCallForwardVarargs operator.

src/mips/interface-descriptors-mips.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_MIPS
 
 #include "src/interface-descriptors.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 159 matching lines @@
 
 
 void CallTrampolineDescriptor::InitializePlatformSpecific(
     CallInterfaceDescriptorData* data) {
   // a1: target
   // a0: number of arguments
   Register registers[] = {a1, a0};
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
 
+void CallForwardVarargsDescriptor::InitializePlatformSpecific(
+    CallInterfaceDescriptorData* data) {
+  // a1: the target to call
+  // a2: start index (to support rest parameters)
+  Register registers[] = {a1, a2};
+  data->InitializePlatformSpecific(arraysize(registers), registers);
+}
 
 void ConstructStubDescriptor::InitializePlatformSpecific(
     CallInterfaceDescriptorData* data) {
   // a1: target
   // a3: new target
   // a0: number of arguments
   // a2: allocation site or undefined
   Register registers[] = {a1, a3, a0, a2};
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
@@ skipping 215 matching lines @@
       a1,  // the JSGeneratorObject to resume
       a2   // the resume mode (tagged)
   };
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS