Instead of doing anything reasonable, Utf8CodePointIterator returned
invalid code points, for example U+123456. However, many callers of this
iterator assume that a code point is always at most 0x10FFFF.
In fact, this is one of two reasons for the following OSS Fuzz issue:
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=49184
This is probably a very old bug.
In the particular case of URLParser, AK::is_url_code_point got confused:
return /* ... */ || code_point >= 0xA0;
If code_point is a "code point" beyond 0x10FFFF, this violates the
condition given in the preceding comment, but satisfies the given
condition, which eventually causes URLParser to crash.
This commit fixes *only* the erroneous UTF-8 decoding, and does not
fully resolve OSS-Fuzz#49184.
ff8f3814cc