feat: introduce puppeteer-firefox (#3628)

This adds a proof-of-concept of `puppeteer-firefox`.
This consists of two parts:
- `//experimental/juggler` - patches to apply to Firefox.
- `//experimental/puppeteer-firefox` - front-end code to
be merged with Puppeteer.

As things become more stable, we'll gradually move it out of
the experimental folder.

experimental/puppeteer-firefox/test/puppeteer.spec.js

@@ -0,0 +1,96 @@
+/**
+ * Copyright 2018 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+const path = require('path');
+const GoldenUtils = require('./golden-utils');
+const {Matchers} = require('@pptr/testrunner');
+
+module.exports.addTests = ({testRunner, product, puppeteer}) => testRunner.describe(product, () => {
+  const {describe, xdescribe, fdescribe} = testRunner;
+  const {it, fit, xit} = testRunner;
+  const {beforeAll, beforeEach, afterAll, afterEach} = testRunner;
+
+  const GOLDEN_DIR = path.join(__dirname, 'golden-' + product);
+  const OUTPUT_DIR = path.join(__dirname, 'output-' + product);
+  const {expect} = new Matchers({
+    toBeGolden: GoldenUtils.compare.bind(null, GOLDEN_DIR, OUTPUT_DIR)
+  });
+
+  beforeAll(state => {
+    state.defaultBrowserOptions = {
+      handleSIGINT: false,
+      dumpio: (process.env.DUMPIO || 'false').trim().toLowerCase() === 'true',
+      args: product === 'chromium' ? ['--no-sandbox'] : [],
+    };
+  });
+  afterAll(state => {
+    state.defaultBrowserOptions = undefined;
+  });
+
+  require('./launcher.spec.js').addTests({testRunner, expect, product, puppeteer});
+  require('./ignorehttpserrors.spec.js').addTests({testRunner, expect, product, puppeteer});
+
+  describe('Browser', () => {
+    beforeAll(async state => {
+      state.browser = await puppeteer.launch(state.defaultBrowserOptions);
+    });
+
+    afterAll(async state => {
+      await state.browser.close();
+      state.browser = null;
+    });
+
+    require('./browser.spec.js').addTests({testRunner, expect, product, puppeteer});
+
+    describe('Page', () => {
+      beforeEach(async state => {
+        state.page = await state.browser.newPage();
+      });
+
+      afterEach(async state => {
+        await state.page.close();
+        state.page = null;
+      });
+
+      require('./page.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./evaluation.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./navigation.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./dialog.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./frame.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./jshandle.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./elementhandle.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./target.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./waittask.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./queryselector.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./emulation.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./screenshot.spec.js').addTests({testRunner, expect, product, puppeteer});
+
+      // Input tests
+      require('./keyboard.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./mouse.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./click.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./type.spec.js').addTests({testRunner, expect, product, puppeteer});
+      require('./hover.spec.js').addTests({testRunner, expect, product, puppeteer});
+
+      // Browser-specific page tests
+      if (product === 'firefox')
+        require('./firefoxonly.spec.js').addTests({testRunner, expect, product, puppeteer});
+      else
+        require('./chromiumonly.spec.js').addTests({testRunner, expect, product, puppeteer});
+    });
+  });
+});
+
+