Don't ignore 'capabilities' flavor extra_spec

The ComputeCapabilitiesFilter would improperly ignore an extra spec of
'capabilities' since it matched the scope name.  When it's not scoped,
it should be treated as an unscoped extra_spec.

Fix bug 1198941.

Change-Id: I781754ae0cb9b2a9f7e7e973f4531f2a99a98d86
Merge "Don't ignore 'capabilities' flavor extra_spec"