Added tests for first-letter pseudo element with preceding punctuatio…

[johannesodland]

…n and intervening spaces.

[johannesodland]

This test is to test that ::first-letter includes space separators (and preceding punctuation) as described in w3c/csswg-drafts#5154.

The Editor's Draft has been updated here: https://drafts.csswg.org/css-pseudo-4/#first-letter-pseudo

The updated text includes the following:

Punctuation (i.e, characters that belong to the Punctuation (P*) Unicode general category [UAX44]) that precedes or follows the first typographic letter unit and any intervening space separators (characters that belong to the Zs Unicode general category [UAX44]) must also be included in the ::first-letter pseudo-element.

This is the first time I'm submitting a test. I'm happy to provide a more thorough test and better documentation of the features it tests if someone can point me to a good test-example.