“The end of TenFourFox and what I've learned from it.”

Nowadays front ends have become impossible to debug by outsiders and the liberties taken by JavaScript minifiers are demonstrably not portable. No one cares because it works okay on the subset of browsers they want to support, but someone bringing up the rear like we are has no chance because you can't look at the source map and no one on the dev side has interest in or time for helping out the little guy. Making test cases from minified JavaScript is an exercise in untangling spaghetti that has welded itself together with superglue all over your chest hair, worsened by the fact that stepping through JavaScript on geriatic hardware with a million event handlers like waiting mousetraps is absolute agony. With that in mind, who's surprised there are fewer and fewer minority browser engines?