Improve JSON stringify in support.html.
Improve JSON stringify in support.html.

This improves the code in support.html that stringifies a JavaScript
object.  Before, it assumed a specific layout. This adds a more
general stringify method that will support nested objects correctly.

Change-Id: Ie59747d0ce634ef028c4819b92fc2fd61552f724

baconz/shaka-player,tvoli/shaka-player,indiereign/shaka-player,brightcove/shaka-player,vimond/shaka-player,TheModMaker/shaka-player,shaka-project/shaka-player,TobbeEdgeware/shaka-player,russitto/shaka-player,Ross-cz/shaka-player,baconz/shaka-player,Ross-cz/shaka-player,shaka-project/shaka-player,Ross-cz/shaka-player,brightcove/shaka-player,indiereign/shaka-player,TobbeEdgeware/shaka-player,brightcove/shaka-player,TheModMaker/shaka-player,russitto/shaka-player,TobbeEdgeware/shaka-player,baconz/shaka-player,vimond/shaka-player,TheModMaker/shaka-player,indiereign/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,TheModMaker/shaka-player,vimond/shaka-player,tvoli/shaka-player,tvoli/shaka-player,russitto/shaka-player,shaka-project/shaka-player