With while-loop versions, `while (pos < end && s.charCodeAt(pos) === 32)
pos++` took a version whose guard could never hold. The counter scan
records only typed-array accesses, so the string read fell back to the
statically ranged check. For a counter held in an int32 slot, that check
asks for a length above 2^31 - 2. The loop paid for the guard and ran its
checked copy.
The counter scan now records `s.charCodeAt(i)` and `s.charAt(i)` of a
string like typed-array reads. Their guard compares the counter's bound
with the string's length, as for a typed array. Corpus 7302 adds while
loops over counters below a string's length.
Chris Tate
8bc8fc54ca