Fix polygerrit_plugin rule to include deps

This allows plugins to depend on bower_component libraries (deps of
polygerrit_plugin and polygerrit_bundle are always bower components,
see also the 'zips' variable in _bundle_impl).

This prepares a fix in the image-diff plugin, which had to use an asset
to pull in the resemblejs library, which made it more complicated and
more difficult to import into google3.

Change-Id: Idb562f44f5781b6e588a156a44cd39f853afaec6
(cherry picked from commit 027551fb11)

tools/bzl/js.bzl

@@ -425,7 +425,7 @@ def bundle_assets(*args, **kwargs):
     """Combine html, js, css files and optionally split into js and html bundles."""
     _bundle_rule(pkg = native.package_name(), *args, **kwargs)
 
-def polygerrit_plugin(name, app, srcs = [], assets = None, plugin_name = None, **kwargs):
+def polygerrit_plugin(name, app, srcs = [], deps = [], assets = None, plugin_name = None, **kwargs):
     """Bundles plugin dependencies for deployment.
 
     This rule bundles all Polymer elements and JS dependencies into .html and .js files.
@@ -450,6 +450,7 @@ def polygerrit_plugin(name, app, srcs = [], assets = None, plugin_name = None, *
             name = name + "_combined",
             app = app,
             srcs = srcs,
+            deps = deps,
             pkg = native.package_name(),
             **kwargs
         )