Bug #224886: Valid RegExp that causes syntax error

Testcase

You should see "Test passed" alert.
If it didn't show up, open Message Console and look for "Inline script compilation error".

Description

This is the code that causes syntax error in Opera Message Console:
var validRegExp = /xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx[y]{2,}z/;
Something in this regexp causes syntax error in Opera.
RegExp itself is valid. It searches for 93 "x", two or more "y" and "z" at the end.

It needs to meet these requirements to cause syntax error: Such error will invalidate whole script block and so can cause serious problems.
diz courtesy of zajec.net