Slider: drag should start only for left mouse button
(cherry picked from commit 93f0caa23eebec9cf87d35989337bef174f7a638)
Slider: De-linting
(cherry picked from commit a492a582ad9ca86df5f09bc92c42b38fcd5586e3)
Unit tests: Slider: Fixing input label and converting left-mouse-button-only test to asynchronous, detailedEventCascade-based test.
(cherry picked from commit 33cb33e49c8674f0d55caaa4a0241ddfc0df7b95)
Slider: event.which for mousedown can be 0 or 1, because it is 0 on mobile and 1 (left mouse button) on desktop.
(cherry picked from commit cd2e2c0f91b2b21d54f9436bd67043eb161c8aab)
Unit tests: Slider: Allow both 0 and 1 for event.which test.
(cherry picked from commit 12c07c1714d1822d72a4e6883bfc5ba838544209)