Update polymer-bundler version to 4.0.9

I have followed that documentation at
https://gerrit-review.googlesource.com/Documentation/dev-bazel.html#npm-binary

I have uploaded a new tgz to the storage bucket.

But we may want to consolidate this somehow with
https://gerrit.googlesource.com/gerrit/+/master/package.json

Change-Id: Ie8da5448e93a0dd09decb01c62f311fbc728ef25

lib/js/npm.bzl

diff --git a/lib/js/npm.bzl b/lib/js/npm.bzl
index 8a9e1ee..5a6a8c0 100644
--- a/lib/js/npm.bzl
+++ b/lib/js/npm.bzl
@@ -1,11 +1,11 @@
 NPM_VERSIONS = {
     "bower": "1.8.8",
     "crisper": "2.0.2",
-    "polymer-bundler": "4.0.2",
+    "polymer-bundler": "4.0.9",
 }
 
 NPM_SHA1S = {
     "bower": "82544be34a33aeae7efb8bdf9905247b2cffa985",
     "crisper": "7183c58cea33632fb036c91cefd1b43e390d22a2",
-    "polymer-bundler": "6b296b6099ab5a0e93ca914cbe93e753f2395910",
+    "polymer-bundler": "c80c9815690d76656d1fa6a231481850b4fa3874",
 }