From a7a84e45c011ad74d2c79394786e8d7e71a6fb34 Mon Sep 17 00:00:00 2001
From: Roan Kattouw <roan.kattouw@gmail.com>
Date: Mon, 22 Jul 2013 18:18:01 -0700
Subject: [PATCH] resourceloader: Never defer execution for top loading modules

There was a bug where if a module was in the top queue but had CSS,
its execution would be deferred until its CSS was ready. This would
cause the module's execution to occur after document ready and after
user scripts had run.

This is bad because top-loaded modules are supposed to be guaranteed
to run before document ready.

Fix this by skipping the wait-for-CSS logic when loading synchronously.
Top-loading modules' execution is now guaranteed to block loading the
rest of the page, but their CSS isn't guaranteed to be ready at this
point. Which is fine, because they shouldn't be measuring things in the
DOM before document ready anyway.

Change-Id: I5779cdef336be184741ad97ea84113eb7790dd39
---
 resources/mediawiki/mediawiki.js | 51 ++++++++++++++++++--------------
 1 file changed, 29 insertions(+), 22 deletions(-)

diff --git a/resources/mediawiki/mediawiki.js b/resources/mediawiki/mediawiki.js
index 0bf4ec3c58..39093e3e6a 100644
--- a/resources/mediawiki/mediawiki.js
+++ b/resources/mediawiki/mediawiki.js
@@ -1026,30 +1026,37 @@ var mw = ( function ( $, undefined ) {
 					mw.messages.set( registry[module].messages );
 				}
 
-				// Make sure we don't run the scripts until all (potentially asynchronous)
-				// stylesheet insertions have completed.
-				( function () {
-					var pending = 0;
-					checkCssHandles = function () {
-						// cssHandlesRegistered ensures we don't take off too soon, e.g. when
-						// one of the cssHandles is fired while we're still creating more handles.
-						if ( cssHandlesRegistered && pending === 0 && runScript ) {
-							runScript();
-							runScript = undefined; // Revoke
-						}
-					};
-					cssHandle = function () {
-						var check = checkCssHandles;
-						pending++;
-						return function () {
-							if (check) {
-								pending--;
-								check();
-								check = undefined; // Revoke
+				if ( $.isReady || registry[module].async ) {
+					// Make sure we don't run the scripts until all (potentially asynchronous)
+					// stylesheet insertions have completed.
+					( function () {
+						var pending = 0;
+						checkCssHandles = function () {
+							// cssHandlesRegistered ensures we don't take off too soon, e.g. when
+							// one of the cssHandles is fired while we're still creating more handles.
+							if ( cssHandlesRegistered && pending === 0 && runScript ) {
+								runScript();
+								runScript = undefined; // Revoke
 							}
 						};
-					};
-				}() );
+						cssHandle = function () {
+							var check = checkCssHandles;
+							pending++;
+							return function () {
+								if (check) {
+									pending--;
+									check();
+									check = undefined; // Revoke
+								}
+							};
+						};
+					}() );
+				} else {
+					// We are in blocking mode, and so we can't afford to wait for CSS
+					cssHandle = function () {};
+					// Run immediately
+					checkCssHandles = runScript;
+				}
 
 				// Process styles (see also mw.loader.implement)
 				// * back-compat: { <media>: css }
-- 
2.20.1