Enable downscale of very large images when uploading on IO thread (fl…

…utter#5011)

lib/ui/painting/codec.cc

@@ -63,7 +63,7 @@ static sk_sp<SkImage> DecodeImage(fml::WeakPtr<GrContext> context,
     // This indicates that we do not want a "linear blending" decode.
     sk_sp<SkColorSpace> dstColorSpace = nullptr;
     return SkImage::MakeCrossContextFromEncoded(
-        context.get(), std::move(buffer), false, dstColorSpace.get());
+        context.get(), std::move(buffer), false, dstColorSpace.get(), true);
   } else {
     // Defer decoding until time of draw later on the GPU thread. Can happen
     // when GL operations are currently forbidden such as in the background