Fix component binding specs on IE < 9
Capture jQuery as jQueryInstance to avoid IE < 9 issue

On IE < 9, the line “var jQuery = window.jQuery” overwrites
window.jQuery with undefined even if it was defined before, if executed
in global scope. This didn’t affect the compiled version of KO, but it
meant that when running specs in IE < 9 against knockout-raw.js, jQuery
was always treated as not referenced even if it was referenced.
Custom elements compatibility with IE < 9
Avoid spec false negative on IE < 9 if jQuery isn't referenced
Remove special custom elements message from IE < 9

… because it’s a lot of code for a minor benefit. We could consider
putting it back later if we think it will benefit many developers.