webpack: Transition activity.css to use webpack.

The activity.scss file is added to activity bundle.

templates/analytics/activity.html

@@ -10,7 +10,6 @@
 {% block customhead %}
 {{ super() }}
 {{ render_bundle('activity') }}
-{% stylesheet 'activity' %}
 {% endblock %}
 
 {% block content %}

tools/webpack.assets.json

@@ -1,5 +1,8 @@
 {
-    "activity": "./static/third/sorttable/sorttable.js",
+    "activity": [
+        "./static/third/sorttable/sorttable.js",
+        "./static/styles/activity.scss"
+    ],
     "portico": [
         "./static/js/portico/header.js",
         "./static/styles/portico-styles.scss"

zproject/settings.py

@@ -860,13 +860,6 @@ PIPELINE = {
     'STYLESHEETS': {
         # If you add a style here, please update stylesheets()
         # in frontend_tests/zjsunit/output.js as needed.
-        'activity': {
-            'source_filenames': (
-                'styles/activity.css',
-                'third/thirdparty-fonts.css',
-            ),
-            'output_filename': 'min/activity.css'
-        },
         'stats': {
             'source_filenames': ('styles/stats.css',),
             'output_filename': 'min/stats.css'