We can just compare for strings here.

1 files changed, 1 insertions, 1 deletions

diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js
index 3943963a..109f5b6d 100644
--- a/tools/js-optimizer.js
+++ b/tools/js-optimizer.js
@@ -188,7 +188,7 @@ function traverseChildren(node, traverse, pre, post, stack) {
 //     was stopped, true. Otherwise undefined.
 function traverse(node, pre, post, stack) {
   var type = node[0], result, len;
-  var relevant = !Array.isArray(node[0]);
+  var relevant = typeof node[0] === 'string';
   if (relevant) {
     if (stack) len = stack.length;
     var result = pre(node, type, stack);