https://bugs.webkit.org/show_bug.cgi?id=127371 tracks adding new API for infinite scrolling web sites. Specifically, it adds willrevealbottom, willrevealtop, willrevealleft, and willrevealright event listeners. They should work on overflow:scroll elements too.
webkitwillreveal* was removed in this - https://github.com/WebKit/WebKit/commit/b510eaa58b5cae0049bbda2bfabb7b64b9a20d5e Do we need this bug for any further purposes? I am marking this as "RESOLVED WONTFIX" but reopen if needed.