QString and QStringRef did bounds checking for left/right/mid, whereas
QStringView was asserting on out of bounds.
Relax the behavior for QStringView and do bounds checking on pos/n
as well. This removes a source of potentially hidden errors when porting
from QStringRef (or QString) to QStringView.
Unfortunately, one difference remains, where QByteArray::left/right()
behaves differently (and somewhat more sane) than QString and
QStringRef. We're keeping the difference here, as it has been around
for many years.
Mark left/right/mid as obsolete and to be replaced with the new
first/last/slice methods.
Change-Id: I18c203799ba78c928a4610a6038089f27696c22e
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>