Normalize `input[type="search"]`

Limiting property `-webkit-appearance` to `input[type="search"]` only,
as it's the element this rule is targeting for instead of unnecessarily
applying it to all `.mw-ui-input` elements. Also adding rule to
remove proprietary IE 10-11 clear button. Bringing it on
par with OOjs UI.

Change-Id: Id375fdb86bf7ef3cfbb2f7e198d59be4947e4edb