[corlib] Task never is CompletedSynchronously
[gsharedvt] Allow the SIZEOF opcode in gsharedvt code if it doesn't reference a gsharedvt type. Fixes #22711.
Don't throw TimeZoneNotFoundExceptions when iOS gives us invalid data.

iOS 8 GM lists "Asia/Chita" among its time zones, but when requesting
the time zone data for that time zone, no data is returned.

With this change we ignore time zones without any data when fetching
all the timezones on the system.
[mcs] Don't use `1 naming for compiler generated second level and deeper nested types. Fixes #22893
[jit] Always pass the imt arg to interface calls in gsharedvt methods. Fixes #22624.