This patch aligns Puppeteer testing infrastructure with the approach
we use in Puppeteer-Firefox.
This patch:
- makes all tests accept Puppeteer object as a function argument
rather than require it statically. This way we can pass either
Puppeteer or Puppeteer-Firefox to drive tests.
- renames the `puppeteer.spec.js` into `launcher.spec.js`. The
`puppeteer.spec.js` is now the entry point for all cross-browsers
tests.
Tracing is working on a per-browser level, not per-page. In order
to paralellize these tests effectively and properly, each should run
a designated browser.
Today, we have tests split into multiple files, with files pulling
tests from some other files.
This patch starts explicitly gathering all tests from the same
`test.js` file.
Drive-By: move one test from `browser.spec.js` into `puppeteer.spec.js`
since it starts browser itself.
