Fix wrong results returned by isEnabled

When language filter plugin is disabled and language filter is enabled in code using JFactory::getApplication()->setLanguageFilter(true) calling JLanguageAssociations->isEnabled causes notices and fatal errors and returns wrong result if item associations are in fact disabled.

What happens is that JPluginHelper::getPlugin returns empty array when certain plugin is disabled and since there is no params to be passed to JRegistry and $enabled gets default value.
Several CSS fixes
Merge pull request #3594 from roland-d/cssfixes

[#33721] Several CSS fixes
[Fix][#33037] Email Cloaking causes slower page loading in Firefox (Fix
# 2716)
Merge pull request #3177 from klas/patch-5

Fix wrong results returned by isEnabled