I merged Ivan's latest patch to 3.4/3.5/default. We're unlikely to ever be able to make these docs completely intuitive (as name resolution is genuinely complex), but Ivan's revisions at least mean we're no longer assuming readers know how the name resolution worked prior to the introduction of lexical scoping, and a couple of tricky cases now have inline examples.

I also noticed an existing paragraph in the docs that *I* didn't understand, and filed issue #24796 to cover that. I'm not sure if we should just delete the paragraph, or if we accidentally dropped a compile time error check that didn't have any tests to ensure we were detecting the problem.