Arrange things so that non-child parameters
are always printed before the children. This
greatly helps with readability, which really
suffers when there's hundreds of lines of indented
children between the node start and its parameters.
Update all affected tests.
Base the rewrite on testsuite/css/parser/test-css-parser - we now
require the node file to match a reference node and track the errors it
triggers.
We also no longer use gtester.