Revert "Disable proto assert that fails in browsers"

This reverts commit 9046487.

Author: Stuk

test/asserts/load.js

@@ -22,8 +22,7 @@ QUnit.module("load", function () {
         assert.ok(typeof file === "string");
         JSZip.loadAsync(file)
         .then(function (zip) {
-            // Passes in Node, fails in browsers:
-            // assert.equal(Object.getPrototypeOf(zip.files), zip.files.__proto__); // jshint ignore:line
+            assert.notEqual(Object.getPrototypeOf(zip.files), zip.files.__proto__);
             return zip.file("__proto__").async("string");        })
         .then(function(result) {
             assert.equal(result, "hello\n", "the zip was correctly read.");