781021 - Re-validate scroll offset and zoom whenever a ShadowLayersUpdate happens

Status: RESOLVED DUPLICATE of bug 1806561

(Core :: Graphics: Layers, defect)

Description

[Doug Sherk (:drs) (inactive)]

We're currently just crossing our fingers and hoping that the current scroll offset and zoom are valid whenever a ShadowLayersUpdate happens. Whenever this update comes, it's possible that the CSS content rect will shrink and we will have been left overscrolled. We need to add checks for this.

This will also encompass the double-tap-to-zoom functionality which will need to have its stop position be revalidated under the same circumstances.