Upgrade webpack / webpack-cli

webpack     | 4.1.1  | 4.27.1
webpack-cli | 2.0.12 | 3.1.2

The upgrade of webpack modified our build files and included these
side effects:

* Our linter flagged the usage of bitwise operators in the build files
so I turned that off in our build file lint config (.eslintrc.es5.json)

* Our build file's size increased slightly from 12.1 KB to 12.13 KB
(gzip) so the package.json's bundlesize was updated accordingly.

No deleterious effects were noticed to popups running locally, but the
jump in webpack version included these notable changes:

* Switch from uglify-es to terser minimizer [1]

[1] https://github.com/webpack/webpack/releases/tag/v4.26.0

The upgrade for webpack-cli was a major version jump, but the params
that we pass to it in our package.json file appear to work as before.

Bug: T209314
Change-Id: I1403f2c4d354cf54554a740f8c23176bf80fd3c6

.eslintrc.es5.json

@@ -50,6 +50,7 @@
 		"no-fallthrough": 0,
 		"no-implicit-coercion": 0,
 		"no-catch-shadow": 0,
-		"max-statements-per-line": 0
+		"max-statements-per-line": 0,
+		"no-bitwise": 0
 	}
 }

package.json

@@ -46,13 +46,13 @@
     "wdio-mocha-framework": "0.6.3",
     "wdio-spec-reporter": "0.1.5",
     "webdriverio": "4.14.1",
-    "webpack": "4.1.1",
-    "webpack-cli": "2.0.12"
+    "webpack": "4.27.1",
+    "webpack-cli": "3.1.2"
   },
   "bundlesize": [
     {
       "path": "resources/dist/index.js",
-      "maxSize": "12.1KB"
+      "maxSize": "12.2KB"
     }
   ]
 }