[Interpreter] infrastructure

[penzn]

Provide a buildable skeleton for the interpereter, with end-to end
types, but with lots of gaps in functionality. Unimplemented functions
throw "TODO v128" error; can parse v128 local type and nothing more.

[penzn]

@ngzhian let's join forces if you are still interested in the interpreter.

[ngzhian]

Cool! I have been hacking a bit at the interpreter too, but haven't cleaned it up enough to put up a PR. We went for similar implementation to use Bytes. I've implemented a bit of the parsing for v128.const so it at least chugs through simd_const.wast test case.

ngzhian@d86bf00

[penzn]

@ngzhian, I just noticed the link to your change, the frontend part looks good, may be we can merge it together with this one somehow.

CC/FYI @rossberg, as we are hacking at the interpreter.

[ngzhian]

I think after this is merged I can try to rebase the frontend changes from my patch. That way there is less code to review in each change.

[rossberg]

Looks good!

[penzn]

I think after this is merged I can try to rebase the frontend changes from my patch. That way there is less code to review in each change.

const is needed in order to verify other functionality. Let me know if you need help with the change.

I opened #141 to track progress of adding the interpreter.

@arunetm @dtig should we merge this?