Revert of 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 MathRoundVariantCallFromUnoptimizedCodeDescriptor::
-    InitializePlatformSpecific(CallInterfaceDescriptorData* data) {
+void MathRoundVariantDescriptor::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