Merge pull request phaserjs#4936 from AdamXA/fix-external-fullscreen-api-calls

Fixes external Fullscreen API calls being blocked by fullscreenchange listener

Author: photonstorm

src/scale/ScaleManager.js

@@ -346,16 +346,6 @@ var ScaleManager = new Class({
          */
         this._createdFullscreenTarget = false;
 
-        /**
-         * Internal var that keeps track of the user, or the browser, requesting fullscreen changes.
-         *
-         * @name Phaser.Scale.ScaleManager#_requestedFullscreenChange
-         * @type {boolean}
-         * @private
-         * @since 3.16.2
-         */
-        this._requestedFullscreenChange = false;
-
         /**
          * The dirty state of the Scale Manager.
          * Set if there is a change between the parent size and the current size.
@@ -1238,8 +1228,6 @@ var ScaleManager = new Class({
         {
             var fsTarget = this.getFullscreenTarget();
 
-            this._requestedFullscreenChange = true;
-
             var fsPromise;
 
             if (fullscreen.keyboard)
@@ -1382,8 +1370,6 @@ var ScaleManager = new Class({
 
         if (fullscreen.active)
         {
-            this._requestedFullscreenChange = true;
-
             document[fullscreen.cancel]();
         }
 
@@ -1490,12 +1476,10 @@ var ScaleManager = new Class({
     onFullScreenChange: function ()
     {
         //  They pressed ESC while in fullscreen mode
-        if (!this._requestedFullscreenChange)
+        if (!(document.fullscreenElement || document.webkitFullscreenElement || document.msFullscreenElement || document.mozFullScreenElement))
         {
             this.stopFullscreen();
         }
-
-        this._requestedFullscreenChange = false;
     },
 
     /**