Makes Wildcard bound calc. stable regardless of type order.

Previously some callers of
CompilationUnitTypeOracleUpdater.resolveClass() treated a boolean false
return value as an error and some callers treated it as a warning. As a
result the order of the types being processed could affect the results.
By making all callers treat a false return value as a warning,
consistency is restored.

Change-Id: I48be4ff0d932ac6fa3bc085cf953b273710add39