Freeze in the JavaScript grammar

[aeschli]

Looks like the JS grammar goes into a endless loop with

function t(){
return e.call(this,[t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),"-",t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),"-","4",t._randomHex(),t._randomHex(),t._randomHex(),"-",t._oneOf(t._timeHighBits),t._randomHex(),t._randomHex(),t._randomHex(),"-",t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex(),t._randomHex()].join(""))||this}

The last evaluate regex before freezing is:

Running (?x) (?:
  (?<![_$[:alnum:]])(?:(?<=\.\.\.)|(?<!\.))(\basync)
)? ((?<![})!\]])\s*
  (?=
    # sure shot arrow functions even if => is on new line
(
  [(]\s*
  (
    ([)]\s*:) |                                                                 # ():
    ((\.\.\.\s*)?[_$[:alpha:]][_$[:alnum:]]*\s*:)                                            # [(]param: | [(]...param:
  )
) |
(
  [<]\s*[_$[:alpha:]][_$[:alnum:]]*\s+extends\s*[^=>]                                        # < typeparam extends
) |
# arrow function possible to detect only with => on same line
(
  (<\s*([_$[:alpha:]]|(\{[^\{\}]*\})|(\([^\(\)]*\))|(\[[^\[\]]*\]))([^=<>]|=[^<]|\<\s*([_$[:alpha:]]|(\{[^\{\}]*\})|(\([^\(\)]*\))|(\[[^\[\]]*\]))([^=<>]|=[^<])*\>)*>\s*)?                                                           # typeparameters
  \(\s*([_$[:alpha:]\{\[]([^()]|\((\s*[^()]*)?\))*)?\)                          # parameteres
  (\s*:\s*([^<>\(\)]|\<[^<>]+\>|\([^\(\)]+\))+)?                                # return type
  \s*=>                                                                         # arrow operator
)
  )
)