Remove Uint8ArrayUtils.key

These keys cannot always be used as keys, for example on IE11 where
very large init datas are found in PlayReady content.  Since there
should not be a large number of unique init datas, a linear
suppression pass and a quadratic removeDuplicates should not be a
problem in practice.

Related to pull #176

Change-Id: I9dd9b5e45422544c86dd95686766625a0b336963

lib/util/uint8array_utils.js

@@ -129,13 +129,3 @@ shaka.util.Uint8ArrayUtils.equal = function(arr1, arr2) {
   return true;
 };
 
-
-/**
- * Convert a Uint8Array to a string which can be used as a key in a dictionary.
- * @param {!Uint8Array} arr
- * @return {string}
- */
-shaka.util.Uint8ArrayUtils.key = function(arr) {
-  return Array.prototype.join.apply(arr);
-};
-