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 0.19.2:

  $ buildifier --version
buildifier version: 0.19.2
buildifier scm revision: d39e4d5c25111527369142f16cdb49aa67707313

Change-Id: I1f06cd4596e794981ccc2d9fc2d1da9b17f3973a
diff --git a/lib/polymer_externs/BUILD b/lib/polymer_externs/BUILD
index cd71d64..f07aa2f 100644
--- a/lib/polymer_externs/BUILD
+++ b/lib/polymer_externs/BUILD
@@ -12,10 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-package(default_visibility = ["//visibility:public"])
-
 load("@io_bazel_rules_closure//closure:defs.bzl", "closure_js_library")
 
+package(default_visibility = ["//visibility:public"])
+
 closure_js_library(
     name = "polymer_closure",
     srcs = ["@polymer_closure//file"],