document.createElementNS is null or not an object in IE8

Having $wgDebugToolbar = true and visiting the wiki with IE8 will give
no debug toolbar, using ?debug=true gives a "document.createElementNS is
null or not an object" javascript fatal.

Throw a error. The function 'createSvgElement' will never be called,
because profiling gives a "An ES5 compatible javascript engine
is required for the profile visualization." in IE8.

Change-Id: I763dae7459cb88f892823b9458ed6dd1dbbf3e9d
Merge "document.createElementNS is null or not an object in IE8"