DevTools: Add support for installing node and running eslint over devtools.

third_party/WebKit/Source/devtools/scripts/buildbot/run_eslint.py

+# Copyright 2016 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
+import subprocess
+import sys
+
+scripts_path = path.dirname(path.dirname(path.abspath(__file__)))
+devtools_path = path.dirname(scripts_path)
+eslint_path = path.join(devtools_path, "devtools-node-modules", "third_party", "node_modules", ".bin", "eslint")
+node_path = path.join(scripts_path, "local_node", "runtimes", "4.5.0", "bin", "node")
+
+eslint_proc = subprocess.Popen(
+    args=[node_path, eslint_path, "front_end"],
+    cwd=devtools_path,
+    stdout=subprocess.PIPE,
+    stderr=subprocess.STDOUT)
+(eslint_proc_out, _) = eslint_proc.communicate()
+print(eslint_proc_out)
+
+if eslint_proc.returncode != 0:
+    print("ERRORS DETECTED")
+    sys.exit(1)
+print("No linting errors found")
+sys.exit(0)