Add Lighthouse CI script

.travis.yml

@@ -1,4 +1,12 @@
+sudo: required
+dist: xenial
 language: node_js
+node_js:
+  - '10'
+addons:
+  chrome: stable
 cache: npm
-script: npm run build
+script:
+  - npm run build
+  - ./run_lighthouse.sh
 after_success: npm run sizereport

run_lighthouse.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+npx http-server -p 9000 ./dist &
+
+npm install -g @lhci/cli@next
+
+lhci collect --url=http://localhost:9000/
+
+lhci assert --preset="lighthouse:recommended"
+
+EXIT_CODE=$?
+kill $!
+exit $EXIT_CODE