WebUI: Add helper scripts for referring to node and node_modules paths.

third_party/node/node_modules.py

+#!/usr/bin/env python
+# Copyright 2017 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from os import path as os_path
+
+
+_THIRD_PARTY_NODE_DIR = os_path.join(os_path.dirname(__file__))
+
+
+_THIRD_PARTY_NODE_MODULES_DIR = os_path.join(
+    _THIRD_PARTY_NODE_DIR, 'node_modules')
+
+def _get_binary(*args):
+  return os_path.join(_THIRD_PARTY_NODE_MODULES_DIR, *args)
+
+def get_vulcanize_binary():
+  return _get_binary('vulcanize', 'bin', 'vulcanize')
+
+def get_crisper_binary():
+  return _get_binary('crisper', 'bin', 'crisper')
+
+def get_polymer_css_build_binary():
+  return _get_binary('polymer-css-build', 'bin', 'polymer-css-build')
+
+def get_uglifyjs_binary():
+  return _get_binary('uglifyjs', 'bin', 'uglifyjs')