get_defined_functions are all lowercase

Summary: Increases symfony from 98.68 to 98.82
Closes https://github.com/facebook/hhvm/pull/4192

Reviewed By: @JoelMarcey

Differential Revision: D1669234

Signature: t1:1669234:1415643321:87e1629b58ab39076cfd1d316bca152466b3dcf0
change is_object() to gettype() === 'object' in spl for incomplete_class

Summary: PHP accepts __php_incompatible_class in spl. But objects from that class fail is_object.

This puts symfony from 98.68 to 98.8 percent.

I don't like to do this...
Can we run perf on this? I don't know how bad it is.

Closes https://github.com/facebook/hhvm/pull/4190

Reviewed By: @JoelMarcey

Differential Revision: D1669230

Signature: t1:1669230:1415643326:4fdf2dd7aae73ae07abd66bb0efa2becb2d22e75