[#7207] add comment, support potential future embed source that does not have iframes
[#7207] add comment, support potential future embed source that does not have iframes

heiths/allura,apache/incubator-allura,apache/incubator-allura,lym/allura-git,apache/allura,apache/allura,apache/incubator-allura,apache/allura,apache/allura,lym/allura-git,heiths/allura,lym/allura-git,lym/allura-git,heiths/allura,lym/allura-git,heiths/allura,apache/incubator-allura,heiths/allura,apache/allura