Reland: Add unoptimized/optimized variants of MathFloor TF code stub

src/x64/interface-descriptors-x64.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.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/interface-descriptors.h"
 
@@ skipping 314 matching lines @@
   Register registers[] = {
       rdi,  // callee
       rbx,  // call_data
       rcx,  // holder
       rdx,  // api_function_address
   };
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
 
 
-void MathRoundVariantDescriptor::InitializePlatformSpecific(
-    CallInterfaceDescriptorData* data) {
+void MathRoundVariantCallFromUnoptimizedCodeDescriptor::
+    InitializePlatformSpecific(CallInterfaceDescriptorData* data) {
   Register registers[] = {
       rdi,  // math rounding function
       rdx,  // vector slot id
   };
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
+
+
+void MathRoundVariantCallFromOptimizedCodeDescriptor::
+    InitializePlatformSpecific(CallInterfaceDescriptorData* data) {
+  Register registers[] = {
+      rdi,  // math rounding function
+      rdx,  // vector slot id
+      rbx   // type vector
+  };
+  data->InitializePlatformSpecific(arraysize(registers), registers);
+}
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64