Drop unused rdtsc instruction.

test/cctest/test-disasm-ia32.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 86 matching lines @@
   __ cmpb(ebx, Operand(ebp, ecx, times_2, 0));
   __ cmpb(Operand(ebp, ecx, times_2, 0), ebx);
   __ or_(edx, 3);
   __ xor_(edx, 3);
   __ nop();
   {
     CHECK(CpuFeatures::IsSupported(CPUID));
     CpuFeatureScope fscope(&assm, CPUID);
     __ cpuid();
   }
-  {
-    CHECK(CpuFeatures::IsSupported(RDTSC));
-    CpuFeatureScope fscope(&assm, RDTSC);
-    __ rdtsc();
-  }
   __ movsx_b(edx, ecx);
   __ movsx_w(edx, ecx);
   __ movzx_b(edx, ecx);
   __ movzx_w(edx, ecx);
 
   __ nop();
   __ imul(edx, ecx);
   __ shld(edx, ecx);
   __ shrd(edx, ecx);
   __ bts(edx, ecx);
@@ skipping 335 matching lines @@
   CHECK(code->IsCode());
 #ifdef OBJECT_PRINT
   Code::cast(code)->Print();
   byte* begin = Code::cast(code)->instruction_start();
   byte* end = begin + Code::cast(code)->instruction_size();
   disasm::Disassembler::Disassemble(stdout, begin, end);
 #endif
 }
 
 #undef __