Replace QScriptBagContainer by QIntrusiveList

Replace QScriptBagContainer by QIntrusiveList

QIntrusiveList effectively does the same as
QScriptBagContainer, without the need to inherit a
Node class. Let's avoid the code duplication.

However, QIntrusiveList::remove() and insert()
are less strict than QScriptBagContainer; introduce
QScriptIntrusiveList that performs the same sanity
checks (no duplicate insertion, etc). Ideally these
checks would be merged into QIntrusiveList.

Also rename QJSValuePrivate::reinitialize() to
invalidate(), and make it not call
engine->unregisterValue(this) any more. Values are
only invalidated at engine destruction time, and
it's the engine's responsibility to erase the list.

Change-Id: I60fc61ee8f90a716a285b1dd1bf4d6a08a9349df
Reviewed-on: http://codereview.qt.nokia.com/2628
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@nokia.com>