Cast NaN to float in ExternalFloatArray::SetValue.

TBR=mstarzinger@chromium.org

Review URL: https://chromiumcodereview.appspot.com/9419003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10718 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects.cc

@@ -11757,7 +11757,7 @@ MaybeObject* ExternalUnsignedIntArray::SetValue(uint32_t index, Object* value) {
 
 
 MaybeObject* ExternalFloatArray::SetValue(uint32_t index, Object* value) {
-  float cast_value = OS::nan_value();
+  float cast_value = static_cast<float>(OS::nan_value());
   Heap* heap = GetHeap();
   if (index < static_cast<uint32_t>(length())) {
     if (value->IsSmi()) {