improve assertions message on function pointer errors
mention ASSERTIONS in abort() calls
extra testing for ASSERTIONS == 2
add test for #2175
fix other.test_dangerous_func_cast
sort function signatures in ASSERTIONS=2 abort message dumps, attempting to show most likely related ones first
add test for phi with unreachable source with a 64-bit value
mention that EMSCRIPTEN_KEEPALIVE also exports for you
fix ASSERTIONS output on bad function pointer calls
update other.test_emcc
put emscripten version in emscripten-version.txt, like other repos
add canvas.style.setProperty in headlessCanvas
Merge remote-tracking branch 'upstream/incoming' into incoming