PICTURE_SIZES has been temporarily disabled until Safari branches. Re-enable it when possible.
This commit renamed this from PICTURE_SIZES flag to CURRENTSRC: https://github.com/WebKit/WebKit/commit/4193285d9b1b0365d99a547e89c0a36c2a75b8e7 and then this commit remove 'CURRENTSRC': https://github.com/WebKit/WebKit/commit/e835937bf929110e8e7013ce85bd82ee2f194120 Do we need to do anything here? @Simon & @Said
No, there is nothing to do here.