Under some circumstances that I haven't pinned down yet, WebCore will load libANGLE.dylib instead of libANGLE-shared.dylib. libANGLE.dylib is no longer produced by the build, and old stale copies are just hanging around in people's build directories, including on the bots. This is the root cause of the bot test failures that keep causing our ANGLE updates patches to be rolled back.
Created attachment 389591 [details] Rename libANGLE.a to libANGLE-static.a
Note that there are important steps to take when updating ANGLE. See http://trac.webkit.org/wiki/UpdatingANGLE
Great work James diagnosing this problem from the binaries from the build bots, and coming up with a future-proof fix!
Comment on attachment 389591 [details] Rename libANGLE.a to libANGLE-static.a Unfortunately we can't do this, because the Apple build system will freak out that we're no longer producing a libANGLE.a, even if we update WebCore at the same time because everything is built in isolation. This is why the change to a dylib was eventually called libANGLE-shared.dylib - I learnt the hard way. The good news is that the bots with the stale file have been cleared, and if it happens again we know what to do. We'll also move to libANGLE-shared.dylib soon.
OK, seems like the easiest thing to do is just wait for the shared library switch, and live with the possibility that some people's builds might be broken in the meantime.