Checks that ArrayBuffer exists when doing a hash operation within the browser.

Reference #871

Author: chrisradek

lib/util.js

@@ -469,7 +469,7 @@ var util = {
       var sliceFn = util.arraySliceFn(data);
       var isBuffer = Buffer.isBuffer(data);
       //Identifying objects with an ArrayBuffer as buffers
-      if (util.isBrowser() && data && data.buffer instanceof ArrayBuffer) isBuffer = true;
+      if (util.isBrowser() && ArrayBuffer && data && data.buffer instanceof ArrayBuffer) isBuffer = true;
 
       if (callback && typeof data === 'object' &&
           typeof data.on === 'function' && !isBuffer) {