Don't call scrollIntoView() on mouse/touch operations.

Besides being unnecessary, it causes a screen jump when selecting a choice from
a ComboBox drop down menu on an RTL page w/a horizontal scrollbar on iOS.

Fixes #17739 on 1.8 branch.
(cherry picked from commit 379f77b6849cce213dd1ea58babdff697861a2e1)

Conflicts:
	form/_ListBase.js
	form/_ListMouseMixin.js