Restrict SourceBuffer.remove() for IE11

This makes sure that remove() is called in a way that is compatible
with IE11.  For more information, see #251.

Change-Id: Iabe752713ba74c7bf516b4e7b93bc83cfccdd481

lib/media/media_source_engine.js

@@ -273,6 +273,10 @@ shaka.media.MediaSourceEngine.prototype.appendBuffer =
  */
 shaka.media.MediaSourceEngine.prototype.remove =
     function(contentType, startTime, endTime) {
+  // On IE11, this operation would be permitted, but would have no effect!
+  // See https://github.com/google/shaka-player/issues/251
+  shaka.asserts.assert(endTime < Number.MAX_VALUE,
+      'remove() with MAX_VALUE or POSITIVE_INFINITY is not IE-compatible!');
   return this.enqueueOperation_(
       contentType,
       this.remove_.bind(this, contentType, startTime, endTime));