We need to have the option to properly enable the feature. I'll open a different one for WebKit2 because disable this experimental feature by default probably makes sense.
Created attachment 165079 [details]
CSS regions is still an experimental feature, we can leave the unconditional compilation but we have to at least be able to disable it for the moment. And in webkit1 case even enable it for testing.
After talking to Mihnea we are going to leave the decision to the WebKit Settings.cpp defaults, currently is set to false. So we are going to trust those defaults for these situations and just modify them for experimental features for the stable releases if we feel it is causing issues.
Forgot this was still open, check implementation proposal using an experimental flag in this bug: https://bugs.webkit.org/show_bug.cgi?id=116611