updated description for detune setting and added a check to see if it's available, webkit implementation does not support it

Author: pavle-goloskokovic

v3/src/sound/BaseSound.js

@@ -65,6 +65,9 @@ var BaseSound = new Class({
          * Represents detuning of sound in [cents](https://en.wikipedia.org/wiki/Cent_%28music%29).
          * The range of the value is -1200 to 1200, but we recommend setting it to [50](https://en.wikipedia.org/wiki/50_Cent).
          *
+         * Standards based Web Audio implementation only.
+         * Webkit Web Audio implementation and HTML5 Audio don't support this.
+         *
          * @property {number} detune
          */
         this.detune = 0;

v3/src/sound/webaudio/WebAudioSound.js

@@ -108,6 +108,7 @@ var WebAudioSound = new Class({
         this.source.buffer = this.audioBuffer;
         this.source.connect(this.muteNode);
         this.applyConfig();
+        // TODO add onended event handler to reset sound state
         this.source.start(0, offset, duration);
     },
     /**
@@ -177,7 +178,7 @@ Object.defineProperty(WebAudioSound.prototype, 'detune', {
     },
     set: function (value) {
         this.currentConfig.detune = value;
-        if (this.source) {
+        if (this.source && this.source.detune) {
             this.source.detune.value =
                 Math.max(-1200, Math.min(value + this.manager.detune, 1200));
         }