Split up interfaceCheck.
Split up runInvalidSelectorTest.
Split up the Selectors API level 2 tests.
Only run the relevant tests in the new matches and find/findAll tests.
Remove testType arguments.
Split out matches-specific code from level2-lib.js.
Split out find/findAll-specific code from level2-lib.js.
Make traverse work if the root is not an Element.

In particular, this is done in some of the runSpecialSelectorTests calls.
Merge pull request #1388 from Ms2ger/selectors-api-in-place

Restructure selectors-api tests.