Restore using ChunkManifestPlugin

Removed this as previously was worried that this was part of why
redeploying with service workers was causing troubles. But as it turned
out, that was caused by not using recordPath (see #533) so this should
be safe to reenable.

lib/utils/static-entry.js

@@ -40,17 +40,18 @@ module.exports = (locals, callback) => {
       }
 
       // Add the chunk-manifest as a head component.
-      //const chunkManifest = require('!raw!public/chunk-manifest.json')
-      //headComponents.push(
-        //<script
-          //id="webpack-manifest"
-          //dangerouslySetInnerHTML={{ __html: `
-          ////<![CDATA[
-          //window.webpackManifest = ${chunkManifest}
-          ////]]>
-          //`}}
-        ///>
-      //)
+      const chunkManifest = require('!raw!public/chunk-manifest.json')
+
+      headComponents.push(
+        <script
+          id="webpack-manifest"
+          dangerouslySetInnerHTML={{ __html: `
+          //<![CDATA[
+          window.webpackManifest = ${chunkManifest}
+          //]]>
+          ` }}
+        />
+      )
 
       const scripts = [`commons`, `app`]
       // Path chunk.

lib/utils/webpack.config.js

@@ -219,10 +219,10 @@ module.exports = (program, directory, suppliedStage, webpackPort = 1500, pages =
           // Extract the webpack chunk manifest out of commons.js so commons.js
           // doesn't get changed everytime you build. This increases the cache-hit
           // rate for commons.js.
-          //new ChunkManifestPlugin({
-            //filename: "chunk-manifest.json",
-            //manifestVariable: "webpackManifest"
-          //}),
+          new ChunkManifestPlugin({
+            filename: "chunk-manifest.json",
+            manifestVariable: "webpackManifest"
+          }),
           // Minify Javascript.
           new webpack.optimize.UglifyJsPlugin({
             compress: {