Remove audio-context dependency

audio-context just just a tiny wrapper for making an AudioContext. We can just vendor our own two line version.
audio-context notably caches audio contexts, which causes problems like ScratchAddons/ScratchAddons#6847
when contexts are suspended and resumed

package.json

@@ -29,8 +29,7 @@
   },
   "dependencies": {
     "@turbowarp/nanolog": "^0.2.0",
-    "@turbowarp/startaudiocontext": "^1.0.0",
-    "audio-context": "1.0.1"
+    "@turbowarp/startaudiocontext": "^1.0.0"
   },
   "devDependencies": {
     "babel-core": "6.26.3",

src/AudioEngine.js

@@ -1,5 +1,4 @@
 const StartAudioContext = require('./StartAudioContext');
-const AudioContext = require('audio-context');
 
 const log = require('./log');
 const uid = require('./uid');
@@ -35,13 +34,24 @@ const decodeAudioData = function (audioContext, buffer) {
     });
 };
 
+/**
+ * @returns {AudioContext} A new audio context.
+ */
+const makeAudioContext = () => {
+    const AudioContext = window.AudioContext || window.webkitAudioContext;
+    if (!AudioContext) {
+        throw new Error('Browser does not support AudioContext');
+    }
+    return new AudioContext();
+};
+
 /**
  * There is a single instance of the AudioEngine. It handles global audio
  * properties and effects, loads all the audio buffers for sounds belonging to
  * sprites.
  */
 class AudioEngine {
-    constructor (audioContext = new AudioContext()) {
+    constructor (audioContext = makeAudioContext()) {
         /**
          * AudioContext to play and manipulate sounds with a graph of source
          * and effect nodes.