fetch array buffers in cryptpad-common

www/common/common-util.js

@@ -89,5 +89,15 @@ define([], function () {
         return Math.floor(bytes / 1024 * 100) / 100;
     };
 
+    Util.fetch = function (src, cb) {
+        var xhr = new XMLHttpRequest();
+        xhr.open("GET", src, true);
+        xhr.responseType = "arraybuffer";
+        xhr.onload = function () {
+            return void cb(void 0, new Uint8Array(xhr.response));
+        };
+        xhr.send(null);
+    };
+
     return Util;
 });

www/common/cryptpad-common.js

@@ -66,6 +66,7 @@ define([
     common.fixFileName = Util.fixFileName;
     common.bytesToMegabytes = Util.bytesToMegabytes;
     common.bytesToKilobytes = Util.bytesToKilobytes;
+    common.fetch = Util.fetch;
 
     // import hash utilities for export
     var createRandomHash = common.createRandomHash = Hash.createRandomHash;