Authored via the following command:
$ find test -type f -print0 | \
xargs -0 sed \
-i 's/^\(\s*\)negative:\s*SyntaxError\s*$/\1negative:\n\1 phase: early\n\1 type: SyntaxError/g'
ES2015 reads:
> RegExpUnicodeEscapeSequence :: u{ HexDigits }
>
> - It is a Syntax Error if the MV of HexDigits > 1114111.
Use the MV 0x110000 to assert the lower boundary of values which are
expected to produce the SyntaxError.