Regex flag parsing breaks parsing for long variable names

[forivall]

This one is weird.

forivall@8e37f39

test case (different than the commit, i was able to reduce it here)

============
long identifier repro
============

@switch (f + agagagagagagaga) {
  <button>1</button>
}
---

test output:

  1. long identifier repro:

    (ERROR
      (control_keyword)
      (expression
        (identifier))
      (UNEXPECTED 'g')
      (regular_expression_flags)
      (UNEXPECTED 'g'))))(regular_expression_flags)(UNEXPECTED 'g')(regular_expression_flags)(UNEXPECTED 'g')(regular_expression_flags)(UNEXPECTED 'g')(regular_expression_flags)(UNEXPECTED 'g')(regular_expression_flags)(UNEXPECTED 'g')(regular_expression_flags)(UNEXPECTED ' ')(control_keyword)(UNEXPECTED 'u')(regular_expression_flags)(UNEXPECTED ' ')(UNEXPECTED 'b')(regular_expression_flags)(UNEXPECTED 't')(special_keyword)(number)(UNEXPECTED 'b')(regular_expression_flags)(UNEXPECTED 't')(special_keyword)(regular_expression_flags)(UNEXPECTED 'f')(regular_expression_flags)(UNEXPECTED 't')(UNEXPECTED 'b')(regular_expression_flags)(UNEXPECTED 't')(special_keyword)(number)(UNEXPECTED 'b')(regular_expression_flags)(UNEXPECTED 't')(special_keyword)
)