Fix a couple of cases of using the old (incorrect) value of 19 contiguous bits.
Teach the tracer how to deal with nopped calls (poorly)
Implement a missing IC.
Add in another case to the failure handler
Fix the value tagger so it doesn't need to avoid the second scratch register.
fix some typos (how on earth did those branches get removed? I'm pretty sure they were there.)
Implement a whole bunch of currently-unimplemented instructions.
I really shouldn't be merging anything here...
Merge branch 'arm64' of github.com:sstangl/js-arm64 into arm64