DumpRenderTree disables App Nap since bug 108400, and I just made WebKit2 secondary processes not app nap in bug 144155. But WebKitTestRunner itself can still be suppressed, as far as I can tell.
Created attachment 251808 [details]
This changes process role from TASK_BACKGROUND_APPLICATION to TASK_UNSPECIFIED. I don't know all the ramifications, but at least the patch is not a no-op, and it makes WKTR more like DRT.
Comment on attachment 251808 [details]
View in context: https://bugs.webkit.org/attachment.cgi?id=251808&action=review
This looks sane to me.
> + static id assertion = [[[NSProcessInfo processInfo] beginActivityWithOptions:options reason:@"DumpRenderTree should not be subject to process suppression"] retain];
DumpRenderTree => WebKitTestRunner