Exclude default polymer theme (#6010)

build-scripts/bundle.js

@@ -15,6 +15,7 @@ module.exports.emptyPackages = ({ latestBuild }) => [
   // Contains all color definitions for all material color sets.
   // We don't use it
   require.resolve("@polymer/paper-styles/color.js"),
+  require.resolve("@polymer/paper-styles/default-theme.js"),
   // Loads stuff from a CDN
   require.resolve("@polymer/font-roboto/roboto.js"),
   require.resolve("@vaadin/vaadin-material-styles/font-roboto.js"),

build-scripts/rollup.js

@@ -43,9 +43,7 @@ const createRollupConfig = ({
       preserveEntrySignatures: false,
       plugins: [
         ignore({
-          files: bundle
-            .ignorePackages({ latestBuild })
-            .concat(bundle.emptyPackages({ latestBuild })),
+          files: bundle.emptyPackages({ latestBuild }),
         }),
         resolve({
           extensions,