Remove strong mode support from rest argument creation.

src/arm64/interface-descriptors-arm64.cc

Index: src/arm64/interface-descriptors-arm64.cc
diff --git a/src/arm64/interface-descriptors-arm64.cc b/src/arm64/interface-descriptors-arm64.cc
index 7f1fd7d37dba1c95eb151fb94302f5c44ae65023..485aa780e392309ad3f195839d1b245e74f40796 100644
--- a/src/arm64/interface-descriptors-arm64.cc
+++ b/src/arm64/interface-descriptors-arm64.cc
@@ -68,7 +68,6 @@ const Register ArgumentsAccessNewDescriptor::parameter_pointer() { return x3; }
 const Register RestParamAccessDescriptor::parameter_count() { return x2; }
 const Register RestParamAccessDescriptor::parameter_pointer() { return x3; }
 const Register RestParamAccessDescriptor::rest_parameter_index() { return x4; }
-const Register RestParamAccessDescriptor::language_mode() { return x1; }
 
 
 const Register ApiGetterDescriptor::function_address() { return x2; }