BHV-14133: Adding -webkit prefix for Spinner transforms.

Issue
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The `moon.Spinner` was not properly being centered within its container.

Fix
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This issue did not appear on newer versions of Chrome as the `transform` property became standardized. Adding the `-webkit` prefix corrects the issue.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>