Add a MathFloor stub generated with TurboFan

src/x64/disasm-x64.cc

 // Copyright 2011 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 <assert.h>
 #include <stdarg.h>
 #include <stdio.h>
 
 #include "src/v8.h"
 
@@ skipping 1372 matching lines @@
         AppendToBuffer(",%s,%d", NameOfXMMRegister(regop), (*current) & 3);
         current += 1;
       } else if (third_byte == 0x0b) {
         get_modrm(*current, &mod, &regop, &rm);
          // roundsd xmm, xmm/m64, imm8
         AppendToBuffer("roundsd %s,", NameOfXMMRegister(regop));
         current += PrintRightXMMOperand(current);
         AppendToBuffer(",%d", (*current) & 3);
         current += 1;
       } else if (third_byte == 0x16) {
-        get_modrm(*current, &mod, &regop, &rm);
+        get_modrm(*current, &mod, &rm, &regop);
         AppendToBuffer("pextrd ");  // reg/m32, xmm, imm8
         current += PrintRightOperand(current);
         AppendToBuffer(",%s,%d", NameOfXMMRegister(regop), (*current) & 3);
         current += 1;
       } else if (third_byte == 0x22) {
         get_modrm(*current, &mod, &regop, &rm);
         AppendToBuffer("pinsrd ");  // xmm, reg/m32, imm8
         AppendToBuffer(" %s,", NameOfXMMRegister(regop));
         current += PrintRightOperand(current);
         AppendToBuffer(",%d", (*current) & 3);
@@ skipping 949 matching lines @@
     for (int i = 6 - static_cast<int>(pc - prev_pc); i >= 0; i--) {
       fprintf(f, "  ");
     }
     fprintf(f, "  %s\n", buffer.start());
   }
 }
 
 }  // namespace disasm
 
 #endif  // V8_TARGET_ARCH_X64