Twenty Fifteen: add instant updating of color schemes to the customizer with postMessage.

Props celloexpressions, bradyvercher, westonruter, fixes #29988.




git-svn-id: https://develop.svn.wordpress.org/trunk@30274 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fifteen: updates to customize-preview.js missed in r30274.

Props celloexpressions, See #29988.



git-svn-id: https://develop.svn.wordpress.org/trunk@30275 602fd350-edb4-49c9-b593-d223f7449a82