It's a preliminary change for IMAP bug fixes.
Also,
- Fixed a potential bug in ImapFolder.setFlags where it'd throw
StringIndexOutOfBoundsException if flags is empty.
- Added a generic flag to proguard.flags so that now all methods with
the "ForTest" sufix are automatically preserved.
Turned out it wasn't needed for this CL, but it should come in handy
someday.
Bug 2538076
Change-Id: I49a08afc196c7b7f1f30477dfc38ac5381045d84