[Parser] Parse wast scripts (#6581)

The spec tests use an extension of the standard text format that includes
various commands and assertions used to test WebAssembly implementations. Add a
utility to parse this extended WebAssembly script format and use it in
wasm-shell to check that it parses our spec tests without error. Fix a few
errors the new parser found in our spec tests.

A future PR will rewrite wasm-shell to interpret the results of the new parser,
but for now to keep the diff smaller, do not do anything with the new parser
except check for errors.

0 files changed, 0 insertions, 0 deletions