fix typo in product var name

media/js/mkt/install.js

@@ -19,7 +19,7 @@
         // Show "Install" button if I'm installing from the Reviewer Tools,
         // I already purchased this, or if it's free!
         if (location.pathname.indexOf('/reviewers/') > -1 ||
-            $product.isPurchased || !product.price) {
+            product.isPurchased || !product.price) {
             install(product);
             return;
         }