Fix sweep step for tainted QObject JavaScript wrappers
See https://codereview.qt-project.org/c/qt/qtdeclarative/+/376014
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.
Pick-to: 5.15 6.2
Change-Id: I2bf2630f538af8cbd4bfffcff29d67be6c278265
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit e6b2f88d892dcf396580a61662f569bf69d6d9d1)
Edited by Nate Graham