The resource namespace associated with a WebRenderBridgeChild can change
over time, e.g. due to a tab being moved between windows. We need to
recreate any resource keys as a result of this. The missing glyph atlas
code assumed the namespace was constant, and this could cause issues by
referencing invalid image keys, or even another unrelated image. This
patch makes it properly track the entire image key, not just the handle,
so that it can manage namespace changes properly.
Differential Revision: https://phabricator.services.mozilla.com/D104336
7067bbd819