GF-61350: Prevent using outdated scroll position when scroller size changes.

Issue
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For `ExpandableInputPickerSample`, the `ScrollThumb` appears below the bottom arrow when the picker is closed.

Fix
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The `scrollTop` and `scrollLeft` values used in calculating the new `x` and `y` values to animate to are outdated as the scroller has changed size after the picker has closed. Instead, we calculate updated values to use in these calculations.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>