Fix: Firefox fullscreen api (fixes #239) (#259)

* Fix: Firefox fullscren api (fixes #239)

* Changed override style

* Upmerge master

* Reapply original fix for #239

* Check if browser is currently in fullscreen before canceling fullscreen

---------

Co-authored-by: Brad Simpson <brad.simpson@kineo.com>

Author: oliverfoster

js/mediaLibrariesOverrides.js

@@ -181,6 +181,35 @@ window.mejs.MediaElementPlayer.prototype.setTrack = function (lang) {
 
 };
 
+/**
+ * Fix for firefox fullscreen api
+ * https://github.com/adaptlearning/adapt-contrib-media/issues/239
+ */
+const mediaFeatures = window.mejs.MediaFeatures;
+if (mediaFeatures.hasMozNativeFullScreen) {
+  Object.assign(mediaFeatures, {
+    fullScreenEventName: document.exitFullscreen
+      ? 'fullscreenchange'
+      : 'mozfullscreenchange',
+    requestFullScreen: el => {
+      document.exitFullscreen
+        ? el.requestFullscreen()
+        : el.mozRequestFullScreen();
+    },
+    isFullScreen: () => {
+      return document.exitFullscreen
+        ? Boolean(document.fullscreenElement)
+        : document.mozFullScreen;
+    },
+    cancelFullScreen: el => {
+      if (!mediaFeatures.isFullScreen()) return;
+      document.exitFullscreen
+        ? document.exitFullscreen()
+        : document.mozCancelFullScreen();
+    }
+  });
+}
+
 /**
  * Overwrite mediaelement-and-player enterFullScreen to remove Chrome <17 bug fix (Media issue #255)
 */