chore: make sure Puppeteer bundling works (#3239)

This patch:
- adds "browser" field to the package.json with default
  bundling options.
- introduces "bundle" and "unit-bundle" commands to
  create bundle and test bundle
- starts running bundle tests on Travis Node 8 bots

Fixes #2374.

utils/browser/test.js

@@ -0,0 +1,80 @@
+const path = require('path');
+const fs = require('fs');
+const puppeteer = require('../..');
+const SimpleServer = require('../../test/server/SimpleServer');
+const {TestRunner, Reporter, Matchers} = require('../testrunner/');
+
+const puppeteerWebPath = path.join(__dirname, 'puppeteer-web.js');
+if (!fs.existsSync(puppeteerWebPath))
+  throw new Error(`puppeteer-web is not built; run "npm run bundle"`);
+const puppeteerWeb = fs.readFileSync(puppeteerWebPath, 'utf8');
+
+const testRunner = new TestRunner();
+const {describe, fdescribe, xdescribe} = testRunner;
+const {it, xit, fit} = testRunner;
+const {afterAll, beforeAll, afterEach, beforeEach} = testRunner;
+const {expect} = new Matchers();
+
+const defaultBrowserOptions = {
+  args: ['--no-sandbox']
+};
+
+beforeAll(async state => {
+  const assetsPath = path.join(__dirname, '..', '..', 'test', 'assets');
+  const port = 8998;
+  state.server = await SimpleServer.create(assetsPath, port);
+  state.serverConfig = {
+    PREFIX: `http://localhost:${port}`,
+    EMPTY_PAGE: `http://localhost:${port}/empty.html`,
+  };
+  state.browser = await puppeteer.launch(defaultBrowserOptions);
+});
+
+afterAll(async state => {
+  await Promise.all([
+    state.server.stop(),
+    state.browser.close()
+  ]);
+  state.browser = null;
+  state.server = null;
+});
+
+beforeEach(async state => {
+  state.page = await state.browser.newPage();
+  await state.page.evaluateOnNewDocument(puppeteerWeb);
+  await state.page.addScriptTag({
+    content: puppeteerWeb + '\n//# sourceURL=puppeteer-web.js'
+  });
+});
+
+afterEach(async state => {
+  await state.page.close();
+  state.page = null;
+});
+
+describe('Puppeteer-Web', () => {
+  it('should work over web socket', async({page, serverConfig}) => {
+    const browser2 = await puppeteer.launch(defaultBrowserOptions);
+    // Use in-page puppeteer to create a new page and navigate it to the EMPTY_PAGE
+    await page.evaluate(async(browserWSEndpoint, serverConfig) => {
+      const puppeteer = require('puppeteer');
+      const browser = await puppeteer.connect({browserWSEndpoint});
+      const page = await browser.newPage();
+      await page.goto(serverConfig.EMPTY_PAGE);
+    }, browser2.wsEndpoint(), serverConfig);
+    const pageURLs = (await browser2.pages()).map(page => page.url()).sort();
+    expect(pageURLs).toEqual([
+      'about:blank',
+      serverConfig.EMPTY_PAGE
+    ]);
+    await browser2.close();
+  });
+});
+
+if (process.env.CI && testRunner.hasFocusedTestsOrSuites()) {
+  console.error('ERROR: "focused" tests/suites are prohibitted on bots. Remove any "fit"/"fdescribe" declarations.');
+  process.exit(1);
+}
+
+new Reporter(testRunner);
+testRunner.run();