PHP 7.0 fails to parse `?` before a parameter type (meaning Nullable in
newer versions), so just omit these parameter type declarations in
the testcase until we drop PHP 7.0 support.
Also drop some `var_dump($x);` left over from debugging this testcase.
I missed that this change breaks cpp_static, which seems to be to do
with handling the combined getter and setter we emit for static
member variables. Reverting while I figure out how to handle that.
This reverts commit a277748870.
