Made most properties public. Fix #5531
Made most properties public. Fix #5531

* The `WebAudioSoundManager.createAudioContext` method is no longer private.
* The `WebAudioSoundManager.context` property is no longer private.
* The `WebAudioSoundManager.masterMuteNode` property is no longer private.
* The `WebAudioSoundManager.masterVolumeNode` property is no longer private.
* The `WebAudioSoundManager.destination` property is no longer private.

BeanSeed/phaser,photonstorm/phaser,photonstorm/phaser,spayton/phaser,spayton/phaser,BeanSeed/phaser