Customizer: Only tie header button action events to the header controls.

Merges [28269] to the 3.9 branch.

props danielbachhuber.
fixes #28046. see #27848.

Built from https://develop.svn.wordpress.org/branches/3.9@28270


git-svn-id: http://core.svn.wordpress.org/branches/3.9@28098 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/customize-controls.js

@@ -309,8 +309,8 @@
 
 	api.HeaderControl = api.Control.extend({
 		ready: function() {
-			this.btnRemove        = $('.actions .remove');
-			this.btnNew           = $('.actions .new');
+			this.btnRemove        = $('#customize-control-header_image .actions .remove');
+			this.btnNew           = $('#customize-control-header_image .actions .new');
 
 			_.bindAll(this, 'openMedia', 'removeImage');