Twenty Fifteen: Improve style dependency loading

[ocean90]

The main stylesheet should get Genericons and the Google webfonts as a dependency. The IE specific stylesheet doesn't include any styles for Genericons so the dependency is wrong in this case.

[iandstewart]

In 30692:

Twenty Fifteen: correct stylesheet dependencies.

Props ocean90, fixes #30532.

[nacin]

Per #30678 this ticket needs to be reopened.

[ocean90]

Fine with removing genericons. One line up we already have wp_enqueue_style( 'genericons', ….

[iamtakashi]

Remove Genericon from the main stylesheet dependency.

[lancewillett]

In 30865:

Twenty Fifteen: remove Genericons as a dependency from loading the main stylesheet.

Props iamtakashi, fixes #30532.

[lancewillett]

In 30866:

Twenty Fourteen: remove Genericons as a dependency from loading the main stylesheet and IE-specific stylesheet. See #30532.

[johnbillion]

In 30882:

Twenty Fifteen: remove Genericons as a dependency from loading the main stylesheet.

Merges [30865] to the 4.1 branch.

Props iamtakashi
See #30532.

[johnbillion]

In 30883:

Twenty Fourteen: remove Genericons as a dependency from loading the main stylesheet and IE-specific stylesheet.

Merges [30866] to the 4.1 branch.

See #30532.