Customizer: Properly handle widget settings when activating a previewed theme.

props westonruter, ocean90, gcorne.
fixes #27767.

Built from https://develop.svn.wordpress.org/trunk@28124


git-svn-id: http://core.svn.wordpress.org/trunk@27955 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/customize-widgets.js

@@ -942,6 +942,7 @@
 			params.action = 'update-widget';
 			params.wp_customize = 'on';
 			params.nonce = api.Widgets.data.nonce;
+			params.theme = api.settings.theme.stylesheet;
 
 			data = $.param( params );
 			$inputs = this._getInputs( $widgetContent );
@@ -1614,7 +1615,7 @@
 				widgetNumber = widget.get( 'multi_number' );
 			}
 
-			controlHtml = $( '#widget-tpl-' + widget.get( 'id' ) ).html();
+			controlHtml = $.trim( $( '#widget-tpl-' + widget.get( 'id' ) ).html() );
 			if ( widget.get( 'is_multi' ) ) {
 				controlHtml = controlHtml.replace( /<[^<>]+>/g, function( m ) {
 					return m.replace( /__i__|%i%/g, widgetNumber );