See bug 47064 and bug 47065. In Internet Explorer 8 and 9, when the ResourceLoader tries to load a 32nd stylesheet in debug mode (as determined by document.querySelectorAll('link[rel="stylesheet"], style').length in the IE 8 debug console), this JS error is produced:
"Could not set the href property. Invalid property value."
This is consistent with hitting the 31 stylesheet limit in these IE versions. ResourceLoader should work around this limitation so debug mode can be used with these browsers, even if many extensions (each having a few stylesheets) are installed.
Version: 1.22.0
Severity: normal
URL: http://test2.wikipedia.org/w/index.php?title=Main_Page&action=edit
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=31676