Install Chrome in the Cloud Build process (#124)

* Install Chrome in the Cloud Build process

It's not in the built-in Linux apt repos so we need to manually wget it

* Update package lock file

karma.conf.js

@@ -1,6 +1,14 @@
+process.env.CHROME_BIN = require('puppeteer').executablePath()
+
 module.exports = function(config) {
   config.set({
-    browsers: ['ChromeHeadless'],
+    browsers: ['ChromeHeadlessNoSandbox'],
+    customLaunchers: {
+      ChromeHeadlessNoSandbox: {
+        base: 'ChromeHeadless',
+        flags: ['--no-sandbox']
+      }
+    },
     frameworks: ['jasmine', 'closure'],
     singleRun: true,
     autoWatch: false,