Bug: Xwayland popup not showing

[ZhongYic00]

from linuxdeepin/treeland#287

steps to reproduce:

• run tinywl
• DISPLAY=:1 gtk-demo

reason:
xwayland popup's contentItem is 0x0, no entering this code path on initial surface commit

            if (d->resizeMode == WSurfaceItem::SizeFromSurface)
                d->doResize(d->resizeMode);

possible way to fix:
as in #308 (comment)

if (d->beforeRequestResizeSurfaceStateSeq <= d->surface->handle()->handle()->current.seq) {
        if (d->beforeRequestResizeSurfaceStateSeq != 0) {
            Q_ASSERT(d->beforeRequestResizeSurfaceStateSeq == d->surface->handle()->handle()->current.seq);
            d->beforeRequestResizeSurfaceStateSeq = 0;
        }