Make sure that on x86 we don't generate SSE2 code in the snapshot.

src/x64/assembler-x64.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 456 matching lines @@
     if (f == SAHF && !FLAG_enable_sahf) return false;
     return (supported_ & (static_cast<uint64_t>(1) << f)) != 0;
   }
 
   static bool IsFoundByRuntimeProbingOnly(CpuFeature f) {
     ASSERT(initialized_);
     return (found_by_runtime_probing_only_ &
             (static_cast<uint64_t>(1) << f)) != 0;
   }
 
+  static bool IsSafeForSnapshot(CpuFeature f) {
+    return (IsSupported(f) &&
+            (!Serializer::enabled() || !IsFoundByRuntimeProbingOnly(f)));
+  }
+
  private:
   // Safe defaults include SSE2 and CMOV for X64. It is always available, if
   // anyone checks, but they shouldn't need to check.
   // The required user mode extensions in X64 are (from AMD64 ABI Table A.1):
   //   fpu, tsc, cx8, cmov, mmx, sse, sse2, fxsr, syscall
   static const uint64_t kDefaultCpuFeatures = (1 << SSE2 | 1 << CMOV);
 
 #ifdef DEBUG
   static bool initialized_;
 #endif
@@ skipping 1139 matching lines @@
  private:
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_ASSEMBLER_X64_H_