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

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index fdc000e33c819d3a31ce8be6f5a4d77a4448f673..8d8208d0990fdd0645b8aeae9a00dd809506f89f 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -186,9 +186,7 @@ PredictableCodeSizeScope::~PredictableCodeSizeScope() {
 #ifdef DEBUG
 CpuFeatureScope::CpuFeatureScope(AssemblerBase* assembler, CpuFeature f)
     : assembler_(assembler) {
-  ASSERT(CpuFeatures::IsSupported(f));
-  ASSERT(!Serializer::enabled() ||
-         !CpuFeatures::IsFoundByRuntimeProbingOnly(f));
+  ASSERT(CpuFeatures::IsSafeForSnapshot(f));
   old_enabled_ = assembler_->enabled_cpu_features();
   uint64_t mask = static_cast<uint64_t>(1) << f;
   // TODO(svenpanne) This special case below doesn't belong here!