Add cvtsd2ss into X64 disassembler

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/23894002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16518 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x64/disasm-x64.cc

@@ -1320,6 +1320,8 @@ const char* DisassemblerX64::TwoByteMnemonic(byte opcode) {
       return "addsd";
     case 0x59:  // F2 prefix.
       return "mulsd";
+    case 0x5A:  // F2 prefix.
+      return "cvtsd2ss";
     case 0x5C:  // F2 prefix.
       return "subsd";
     case 0x5E:  // F2 prefix.