Fix BadArgument warnings for non-whole program nemo

Lint can't tell if something is a type alias or an object
unless it sees the file that defines the name.  Check it's not in
WholeProgram mode.

Reviewed By: @markw65

Differential Revision: D965717
Revert "Revert "make simplexml xpath return original objects""

This reverts commit 20c0a8a3c8bf58239fbd856b7f9a83a4c35844bf.

Reviewed By: @edwinsmith

Differential Revision: D964913
Don't treat DOMDocument's fields as always set

Fixes the logic in PropertyAccessorMap::isset. This is for a
fatal in Wordpress tests.

Reviewed By: @ptarjan

Differential Revision: D964025