fix flashing labels in conversation view

No reason to cache the filtered list of folders, so remove the cache.
Its presence broke conversation view's display of folders because we're
now reusing the same Conversation objects from the list view.

Filtering the folder list only happens once per row upon bind(). If
anything, we could move it into the worker thread, but there's no
particular benefit to caching the filtered version.

Bug: 9277845
Change-Id: I12dd2cdd93f87e3f24c0ea6de9c0b715b0e34c61
2 files changed