fix sweep step for tainted QObject JavaScript wrappers

fix sweep step for tainted QObject JavaScript wrappers

Origin: upstream, https://code.qt.io/cgit/qt/qtdeclarative.git/commit/?id=e6b2f88d892dcf39
Last-Update: 2022-02-13

Currently, whenever the garbage collector runs, it will destroy all
valid tainted wrappers.

Only null or undefined wrappers will be preserved in the
m_multiplyWrappedQObjects map.

It seems like "!" was overlooked in
3b5d37ce3841c4bfdf1c629d33f0e33b881b47fb. Prior to that change, it
was "!it.value()->markBit()", so calling erase() in the then branch
did make sense. But with "!it.value().isNullOrUndefined()", erase()
will be called for every valid wrapper, which is the opposite what we
want.

Gbp-Pq: Name fix_sweep_step.patch