Theme Customizer: Don't switch themes and update settings when the enter key is pressed. see #19910.

git-svn-id: https://develop.svn.wordpress.org/trunk@20035 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/js/customize-controls.dev.js

@@ -75,6 +75,12 @@
 			});
 
 			this.refresh();
+
+			// Prevent the form from saving when enter is pressed.
+			this.form.on( 'keydown', function( e ) {
+				if ( 13 === e.which ) // Enter
+					e.preventDefault();
+			});
 		},
 		loader: function() {
 			var self = this,