[wast mode] update to match latest WebAssembly specification
[wast mode] update to match latest WebAssembly specification

Also shorten the regex for the keyword tokens a bit.
dperetti/CodeMirror,wingify/CodeMirror,pabloferz/CodeMirror,wingify/CodeMirror,nightwing/CodeMirror,pabloferz/CodeMirror,hackmdio/CodeMirror,wingify/CodeMirror,nightwing/CodeMirror,pabloferz/CodeMirror,hackmdio/CodeMirror,hackmdio/CodeMirror,nightwing/CodeMirror,dperetti/CodeMirror,dperetti/CodeMirror