update enhance.js to latest

_includes/enhance.js

@@ -27,6 +27,7 @@
 		var ref = window.document.getElementsByTagName( "script" )[ 0 ];
 		var script = window.document.createElement( "script" );
 		script.src = src;
+		script.async = true;
 		ref.parentNode.insertBefore( script, ref );
 		return script;
 	}
@@ -36,18 +37,40 @@
 
 	// loadCSS: load a CSS file asynchronously. Included from https://github.com/filamentgroup/loadCSS/
 	function loadCSS( href, before, media ){
+		// Arguments explained:
+		// `href` is the URL for your CSS file.
+		// `before` optionally defines the element we'll use as a reference for injecting our <link>
+		// By default, `before` uses the first <script> element in the page.
+		// However, since the order in which stylesheets are referenced matters, you might need a more specific location in your document.
+		// If so, pass a different reference element to the `before` argument and it'll insert before that instead
+		// note: `insertBefore` is used instead of `appendChild`, for safety re: http://www.paulirish.com/2011/surefire-dom-element-insertion/
 		var ss = window.document.createElement( "link" );
 		var ref = before || window.document.getElementsByTagName( "script" )[ 0 ];
+		var sheets = window.document.styleSheets;
 		ss.rel = "stylesheet";
 		ss.href = href;
 		// temporarily, set media to something non-matching to ensure it'll fetch without blocking render
 		ss.media = "only x";
 		// inject link
 		ref.parentNode.insertBefore( ss, ref );
-		// set media back to `all` so that the styleshet applies once it loads
-		setTimeout( function(){
-			ss.media = media || "all";
-		} );
+		// This function sets the link's media back to `all` so that the stylesheet applies once it loads
+		// It is designed to poll until document.styleSheets includes the new sheet.
+		function toggleMedia(){
+			var defined;
+			for( var i = 0; i < sheets.length; i++ ){
+				if( sheets[ i ].href && sheets[ i ].href.indexOf( href ) > -1 ){
+					defined = true;
+				}
+			}
+			if( defined ){
+				ss.media = media || "all";
+			}
+			else {
+				setTimeout( toggleMedia );
+			}
+		}
+
+		toggleMedia();
 		return ss;
 	}
 
@@ -152,4 +175,4 @@
 		loadCSS( fonts.content );
 	}
 
-}( this ));
+}( this ));