Fixes first test that failed without jQuery

“Test to make sure the style tag was inserted” is next failing, it’s
looking for `bigtext-id-undefined` instead of the appropriate number,
even though those are being used in the DOM correctly.
Fixes `style` injection test for no-jQuery version
Fixes double `style` injection test for no-jQuery
Fixes all line measurement tests for no-jQuery
Removes jQuery no-conflict test
Fixes remaing tests expecting jQuery dependency
Fixes behaviour when no children are present