Fix spinner hiding on IE
Fix spinner hiding on IE

We can't use the same method to hide the SVG on IE, since it doesn't
have classList there.

Discovered while working on #1749

Change-Id: Ida501375634fcb666af78d89925371e979403a4e

tvoli/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,tvoli/shaka-player