[runtime] Optimize and unify rest parameters.

src/mips64/interface-descriptors-mips64.cc

Index: src/mips64/interface-descriptors-mips64.cc
diff --git a/src/mips64/interface-descriptors-mips64.cc b/src/mips64/interface-descriptors-mips64.cc
index b5731db2f6d73fb15e6943c1a9211fafb6c0f09c..2b5877dbae09594804728841a3095b689549487c 100644
--- a/src/mips64/interface-descriptors-mips64.cc
+++ b/src/mips64/interface-descriptors-mips64.cc
@@ -63,11 +63,6 @@ const Register ArgumentsAccessNewDescriptor::parameter_count() { return a2; }
 const Register ArgumentsAccessNewDescriptor::parameter_pointer() { return a3; }
 
 
-const Register RestParamAccessDescriptor::parameter_count() { return a2; }
-const Register RestParamAccessDescriptor::parameter_pointer() { return a3; }
-const Register RestParamAccessDescriptor::rest_parameter_index() { return a4; }
-
-
 const Register ApiGetterDescriptor::function_address() { return a2; }
 
 
@@ -97,6 +92,13 @@ void FastNewContextDescriptor::InitializePlatformSpecific(
 }
 
 
+void FastNewRestParameterDescriptor::InitializePlatformSpecific(
+    CallInterfaceDescriptorData* data) {
+  Register registers[] = {a1};
+  data->InitializePlatformSpecific(arraysize(registers), registers, NULL);
+}
+
+
 void ToNumberDescriptor::InitializePlatformSpecific(
     CallInterfaceDescriptorData* data) {
   Register registers[] = {a0};