Parsing of nested repeat operators

[tom-lord]

Nested repeat operators are incorrectly parsed, e.g. /b{2}{3}/ - which "should" be interpreted like /b{6}/.

However, there is probably no reason to ever write regexes like this! This behaviour is undocumented by both the language and regexp engine; there is no test for its expected behaviour at the time of writing - therefore such behaviour should not be relied upon.