Only crosscompile binary op stubs if we compile a snapshot.

BUG=
R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/26266005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17130 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/assembler.cc

@@ -211,6 +211,9 @@ CpuFeatureScope::~CpuFeatureScope() {
 
 PlatformFeatureScope::PlatformFeatureScope(CpuFeature f)
     : old_cross_compile_(CpuFeatures::cross_compile_) {
+  // CpuFeatures is a global singleton, therefore this is only safe in
+  // single threaded code.
+  ASSERT(Serializer::enabled());
   uint64_t mask = static_cast<uint64_t>(1) << f;
   CpuFeatures::cross_compile_ |= mask;
 }

src/ia32/code-stubs-ia32.cc

@@ -2918,8 +2918,12 @@ void CodeStub::GenerateStubsAheadOfTime(Isolate* isolate) {
   RecordWriteStub::GenerateFixedRegStubsAheadOfTime(isolate);
   ArrayConstructorStubBase::GenerateStubsAheadOfTime(isolate);
   CreateAllocationSiteStub::GenerateAheadOfTime(isolate);
-  PlatformFeatureScope sse2(SSE2);
-  BinaryOpStub::GenerateAheadOfTime(isolate);
+  if (Serializer::enabled()) {
+    PlatformFeatureScope sse2(SSE2);
+    BinaryOpStub::GenerateAheadOfTime(isolate);
+  } else {
+    BinaryOpStub::GenerateAheadOfTime(isolate);
+  }
 }