Remove quotes around CSS keyframe identifiers

[donnapep]

Fix for #5797.

This PR removes the quotes around some of the CSS keyframe animation names.

Testing
loading-dot-pulse
This animation is applied to the ellipsis at the end of the "Trashing Post..." message when moving a post to the trash.

pulse-light
This animation pulsates the title box briefly when opening a post, before the title is populated.

loading-fade
This animation applies a fade effect to the cards on the Themes page before the images load.

appear
When saving changes to My Profile, this animation fades in the "Settings saved successfully!" message.

This is not a complete list of the scenarios in which these animations are applied, but should suffice for testing purposes.

Test live: https://calypso.live/?branch=fix/keyframe-animation-names

[gwwar]

Thanks for the fix @donnapep! I've verified that the animations are broken in some browsers like FF, and now work with this fix.