diff --git a/wp-includes/js/customize-loader.js b/wp-includes/js/customize-loader.js
index 2ea2c5f0b..80eb2bd30 100644
--- a/wp-includes/js/customize-loader.js
+++ b/wp-includes/js/customize-loader.js
@@ -1 +1 @@
-if(typeof wp==="undefined"){var wp={}}(function(a,c){var b=wp.customize,d;d={initialize:function(){this.body=c(document.body).addClass("customize-support");this.element=c('<div id="customize-container" class="wp-full-overlay" />').appendTo(this.body);c("#wpbody").on("click",".load-customize",function(e){e.preventDefault();d.open(c(this).attr("href"))})},open:function(e){this.iframe=c("<iframe />",{src:e}).appendTo(this.element);this.messenger=new b.Messenger(e,this.iframe[0].contentWindow);this.messenger.bind("ready",function(){d.messenger.send("back",wpCustomizeLoaderL10n.back)});this.messenger.bind("close",function(){d.close()});this.element.fadeIn(200,function(){d.body.addClass("customize-active full-overlay-active")})},close:function(){this.element.fadeOut(200,function(){d.iframe.remove();d.iframe=null;d.messenger=null;d.body.removeClass("customize-active full-overlay-active")})}};c(function(){if(!!window.postMessage){d.initialize()}});b.Loader=d})(wp,jQuery);
\ No newline at end of file
+if(typeof wp==="undefined"){var wp={}}(function(a,c){var b=wp.customize,d;d={supports:{history:!!(window.history&&history.pushState),hashchange:("onhashchange" in window)&&(document.documentMode===undefined||document.documentMode>7)},initialize:function(){this.body=c(document.body).addClass("customize-support");this.window=c(window);this.element=c('<div id="customize-container" class="wp-full-overlay" />').appendTo(this.body);c("#wpbody").on("click",".load-customize",function(e){e.preventDefault();d.open(c(this).attr("href"))});if(this.supports.history){this.window.on("popstate",d.popstate)}if(this.supports.hashchange){this.window.on("hashchange",d.hashchange)}},popstate:function(g){var f=g.originalEvent.state;if(f&&f.customize){d.open(f.customize)}else{if(d.active){d.close()}}},hashchange:function(g){var f=window.location.toString().split("#")[1];if(f&&0===f.indexOf("customize=on")){d.open(wpCustomizeLoaderL10n.url+"?"+f)}if(!f){d.close()}},open:function(e){if(this.active){return}this.active=true;this.iframe=c("<iframe />",{src:e}).appendTo(this.element);this.messenger=new b.Messenger(e,this.iframe[0].contentWindow);this.messenger.bind("ready",function(){d.messenger.send("back",wpCustomizeLoaderL10n.back)});this.messenger.bind("close",function(){if(d.supports.history){history.back()}else{if(d.supports.hashchange){window.location.hash=""}else{d.close()}}});this.element.fadeIn(200,function(){var f=e.split("?")[1];d.body.addClass("customize-active full-overlay-active");if(d.supports.history&&window.location.href!==e){history.pushState({customize:e},"",e)}else{if(d.supports.hashchange&&f){window.location.hash=f}}})},close:function(){if(!this.active){return}this.active=false;this.element.fadeOut(200,function(){d.iframe.remove();d.iframe=null;d.messenger=null;d.body.removeClass("customize-active full-overlay-active")})}};c(function(){if(window.postMessage){d.initialize()}});b.Loader=d})(wp,jQuery);
\ No newline at end of file
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 8c573bf5c..eb06a21dd 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '3.4-beta2-20478';
+$wp_version = '3.4-beta2-20489';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.