Remove SSE2 feature checks from x64 code (it is always on)

src/x64/assembler-x64.cc

 // Copyright 2012 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 132 matching lines @@
 
   typedef uint64_t (*F0)();
   F0 probe = FUNCTION_CAST<F0>(reinterpret_cast<Address>(memory->address()));
 
   uint64_t probed_features = probe();
   uint64_t platform_features = OS::CpuFeaturesImpliedByPlatform();
   supported_ = probed_features | platform_features;
   found_by_runtime_probing_only_
       = probed_features & ~kDefaultCpuFeatures & ~platform_features;
 
-  // SSE2 and CMOV must be available on an X64 CPU.
+  // CMOV must be available on an X64 CPU.
   ASSERT(IsSupported(CPUID));
-  ASSERT(IsSupported(SSE2));
   ASSERT(IsSupported(CMOV));
 
   delete memory;
 }
 
 
 // -----------------------------------------------------------------------------
 // Implementation of RelocInfo
 
 // Patch the code at the current PC with a call to the target address.
@@ skipping 2920 matching lines @@
 bool RelocInfo::IsCodedSpecially() {
   // The deserializer needs to know whether a pointer is specially coded.  Being
   // specially coded on x64 means that it is a relative 32 bit address, as used
   // by branch instructions.
   return (1 << rmode_) & kApplyMask;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64