build: remove dashboard (#14023)

* Since we going to move from Travis to CircleCI we don't want to use the dashboard anymore. Since nobody has been
looking at the dashboard frequently, it just makes things more complicated and additionally we will be using
the Github robot in order to keep track of size changes.

package.json

@@ -111,7 +111,6 @@
     "karma": "^3.0.0",
     "karma-browserstack-launcher": "^1.3.0",
     "karma-chrome-launcher": "^2.2.0",
-    "karma-coverage": "^1.1.1",
     "karma-firefox-launcher": "^1.0.1",
     "karma-jasmine": "^1.1.2",
     "karma-sauce-launcher": "^1.2.0",