Update style of TagNode tests
Update style of TagNode tests

Change them to use one-line `it` blocks where possible.

Change-Id: I1f3eca26c571369426c8e79745209e3dc96572e0
Reviewed-on: http://gerrit.causes.com/45300
Tested-by: jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@brigade.com>
Reviewed-by: Shane da Silva <67fb7bfe39f841b16a1f86d3928acc568d12c716@brigade.com>

skateman/haml-lint,mzp/haml-lint