Scaled cursor support is protected by ENABLE_MOUSE_CURSOR_SCALE flag. However, turning it on is not sufficient to support scaled cursors in WebKit2 because the WebCore::Cursor's scale is not serialized in WK2 IPC.
Created attachment 181922 [details]
The UI process side may not need it actually. I'll double check and close the bug if that is the case.
Comment on attachment 181922 [details]
Attachment 181922 [details] did not pass mac-ews (mac):
It is not needed on UI side. Sorry for the noise.