Backed out 2 changesets (bug 1724106) for causing Bug 1728715.

CLOSED TREE

Backed out changeset 81d1db229eea (bug 1724106)
Backed out changeset 8ed4675541c6 (bug 1724106)

dom/html/HTMLMediaElement.cpp

@@ -7374,8 +7374,6 @@ void HTMLMediaElement::AsyncRejectPendingPlayPromises(nsresult aError) {
 }
 
 void HTMLMediaElement::GetEMEInfo(dom::EMEDebugInfo& aInfo) {
-  MOZ_ASSERT(NS_IsMainThread(),
-             "MediaKeys expects to be interacted with on main thread!");
   if (!mMediaKeys) {
     return;
   }