fix(notify): bound RowStride before the int64 guard

The dimension cap closed the named overflow, but stride was still
r.RowStride whenever RowStride >= Width*Channels, and asInt accepts an
int64 wire value. With Width=2, Height=2, RowStride=MaxInt the int64
need product wraps negative, the guard passes, and r.Data[y*stride:]
panics at y=1. Reject a negative stride and any stride above
Width*Channels+4096, which is the real packing plus alignment slack.
After the cap and this bound neither need nor y*stride can overflow, so
the comment now says so.

0 files changed, 0 insertions, 0 deletions