Fix conditional on sse2 support in CompileMathFloor

src/ia32/stub-cache-ia32.cc

 // Copyright 2006-2009 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 1905 matching lines @@
                                                     JSFunction* function,
                                                     String* name) {
   // ----------- S t a t e -------------
   //  -- ecx                 : name
   //  -- esp[0]              : return address
   //  -- esp[(argc - n) * 4] : arg[n] (zero-based)
   //  -- ...
   //  -- esp[(argc + 1) * 4] : receiver
   // -----------------------------------
 
-  if (isolate()->cpu_features()->IsSupported(SSE2)) {
+  if (!isolate()->cpu_features()->IsSupported(SSE2)) {
     return isolate()->heap()->undefined_value();
   }
 
   CpuFeatures::Scope use_sse2(SSE2);
 
   const int argc = arguments().immediate();
 
   // If the object is not a JSObject or we got an unexpected number of
   // arguments, bail out to the regular call.
   if (!object->IsJSObject() || argc != 1) {
@@ skipping 1767 matching lines @@
 
   return GetCode(flags);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32