fix #481 selectionKey/AutoCompleteModifier fail in IE

This is a temporary fix to make the test pass in IE, by changing the
modifier from Ctrl to Shift.

A new test with `ctrl` as a modifier should be added later. Perhaps an update of Syn will be needed. This commit: https://github.com/bitovi/syn/commit/c77936b3b625428441fc01d337dfd79186c48400 partially resolves the issue but not entirely.