Bazel: Automatically fix lint errors with buildifier

In recent buildifier versions, lint errors can be fixed automatically:

  $ find . \( -name BUILD -o -name "*.bzl" \) -print \
      | xargs buildifier --lint=fix

This commit was created with Buildifier version 0.22.0:

  $ buildifier --version
buildifier version: 0.22.0
buildifier scm revision: 55b64c3d2ddfb57f06477c1d94ef477419c96bd6

Change-Id: I01c0a9ff5418270e86f3f9206c4c89fa8d174553
diff --git a/BUILD b/BUILD
index 4733856..c97e62e 100644
--- a/BUILD
+++ b/BUILD
@@ -2,8 +2,11 @@
 
 polygerrit_plugin(
     name = "image-diff",
-    srcs = glob(["**/*.html", "**/*.js"]),
-    externs = ["externs.js"],
+    srcs = glob([
+        "**/*.html",
+        "**/*.js",
+    ]),
     app = "plugin.html",
+    externs = ["externs.js"],
     deps = ["//lib/js:resemblejs"],
 )