I believe this refers to the constellation of work surrounding the ReShape hidden class datastructure refactoring https://bugzilla.mozilla.org/show_bug.cgi?id=r

I believe this refers to the constellation of work surrounding the ReShape hidden class datastructure refactoring https://bugzilla.mozilla.org/show_bug.cgi?id=reshape https://bugzilla.mozilla.org/show_bug.cgi?id=reshape There was an initial change and then various bits of followup work to take advantage of it. (Ah. mccr8 says it's Stencil. That probably makes more sense.)