Add PolyLint Bazel rule

To install the linter:
  npm install -g polylint

To run the linter:
  bazel test //polygerrit-ui/app:polylint_test

Change-Id: I552f6eedce0e4e90d394acfc516940a8c26e948f

polygerrit-ui/README.md

@@ -148,3 +148,17 @@ Some useful commands:
 `eslint --ext .html,.js polygerrit-ui/app/$YOUR_DIR_HERE`
 * To run the linter on all of your local changes:
 `git diff --name-only master | xargs eslint --ext .html,.js`
+
+We also use the polylint tool to lint use of Polymer. To install polylint,
+execute the following command.
+
+```sh
+npm install -g polylint
+```
+
+To run polylint, execute the following command.
+
+```sh
+bazel test //polygerrit-ui/app:polylint_test
+```
+

polygerrit-ui/app/BUILD

@@ -129,6 +129,16 @@ filegroup(
     ),
 )
 
+filegroup(
+    name = "bower_components",
+    srcs = glob(
+        [
+            "bower_components/**/*.html",
+            "bower_components/**/*.js",
+        ]
+    ),
+)
+
 genrule2(
     name = "pg_code_zip",
     srcs = [":pg_code"],
@@ -172,3 +182,18 @@ sh_test(
         "manual",
     ],
 )
+
+sh_test(
+    name = "polylint_test",
+    size = "large",
+    srcs = ["polylint_test.sh"],
+    data = [
+        ":pg_code",
+        ":bower_components",
+    ],
+    # Should not run sandboxed.
+    tags = [
+        "local",
+        "manual",
+    ],
+)

polygerrit-ui/app/polylint_test.sh

@@ -0,0 +1,18 @@
+#!/bin/sh
+
+set -ex
+
+npm_bin=$(which npm)
+if [[ -z "$npm_bin" ]]; then
+    echo "NPM must be on the path."
+    exit 1
+fi
+
+polylint_bin=$(which polylint)
+if [[ -z "$polylint_bin" ]]; then
+    echo "You must install polylint and its dependencies from NPM."
+    echo "> npm install -g polylint"
+    exit 1
+fi
+
+${polylint_bin} --root polygerrit-ui/app --input elements/gr-app.html