Add both node paths to both Polymer steps.

scripts/slave/recipes/polymer.expected/polymer-win.json

Index: scripts/slave/recipes/polymer.expected/polymer-win.json
diff --git a/scripts/slave/recipes/polymer.expected/polymer-win.json b/scripts/slave/recipes/polymer.expected/polymer-win.json
index baeafa8433d08af8cea45c57a0882d3613e2f83f..fcb00efefa5f02475b9df86eaae95539399e05f3 100644
--- a/scripts/slave/recipes/polymer.expected/polymer-win.json
+++ b/scripts/slave/recipes/polymer.expected/polymer-win.json
@@ -19,14 +19,14 @@
   {
    "cmd": ["npm.cmd", "install"],
    "cwd": "[SLAVE_BUILD_ROOT]\\polymer",
-   "env": {"PATH": "C:\\Program Files (x86)\\nodejs;%(PATH)s"},
+   "env": {"PATH": "C:\\Program Files (x86)\\nodejs;C:\\Users\\chrome-bot\\AppData\\Roaming\\npm;%(PATH)s"},
    "name": "update-install"
   },
   {
    "allow_subannotations": true,
    "cmd": ["grunt.cmd", "test-buildbot"],
    "cwd": "[SLAVE_BUILD_ROOT]\\polymer",
-   "env": {"PATH": "C:\\Users\\chrome-bot\\AppData\\Roaming\\npm;%(PATH)s"},
+   "env": {"PATH": "C:\\Program Files (x86)\\nodejs;C:\\Users\\chrome-bot\\AppData\\Roaming\\npm;%(PATH)s"},
    "name": "test"
   }
 ]