Merge hidden_span_if and hidden_div_if

Merged `hidden_span_if` with `hidden_div_if`. They both call `hidden_tag_if` for purposes of good and evil.

Net net, it is only -2 lines. But it opens up any tag being able to use the hidden logic.

While it would be nice if we could go towards the block version, there are currently 58 that use blocks and 110 that do not.
Apparently, there are only 12 instances of the `hidden_span_if`, most of which have a block.

@dclarizio