trigger CAPTION_RENDERED for caption cea608 too.

Author: nicosang

src/streaming/text/TextTracks.js

@@ -430,6 +430,7 @@ function TextTracks() {
                         } else {
                             captionContainer.appendChild(this.cueHTMLElement);
                             scaleCue.call(self, this);
+                            eventBus.trigger(Events.CAPTION_RENDERED, {captionDiv: this.cueHTMLElement, currentTrackIdx});
                         }
                     }
                 };