Don't grow container when desired size is known

Don't grow container when desired size is known

QList<Type>::reserve() is used upfront to allocate necessary memory in a one
go. This tells us straight away whether allocation is possible at all and
reduces re-allocations and consequent memory copies.

This also has the side effect that no spare memory is allocated, also allowing
up to (and including) INT_MAX elements to actually be stored in the underlying
QList, as long as enough memory is available to satisfy the allocation request
and subsequent fill.

The qqmlecmascript::sequenceConversionIndexes was changed to not attempt
INT_MAX allocations as, given enough memory and virtual address space, that
might succeed but take a really long time.

Change-Id: I4b0c965e9c23be78874343a70d7c155933c80903
Reviewed-by: Chris Adams <christopher.adams@nokia.com>
Reviewed-by: Kent Hansen <kent.hansen@nokia.com>