Sequential scalars in a regex literal combined into a single character

[natecook1000]

In a comment to [#82424], a different issue is highlighted by @stefanspringer1. Here the two scalar literals \x{33C}\x{347} are meant to represent the end of one range and the start of another, but the parser treats them as a single character/grapheme cluster, which is in turn invalid as the bound of a character class range.

...It is not only about an isolated range, but:

 _ = "abc".contains(#/[\x{31C}-\x{333}]/#) // OK
 _ = "abc".contains(#/[\x{339}-\x{33C}\x{347}-\x{349}]/#) // error: '̼͇' is an invalid bound for character class range
 _ = "abc".contains(#/[\x{347}-\x{349}]/#) // OK

Note that in the middle the ranges from the first and the last expression are both used sequentially.