Refactor lifecycle tests and add any missing tests

[ankur22]

Before we attempt to cleanup the lifecycle event code (#593) we need to lock in the current behaviour so that any refactoring does not affect the behaviour.

The tests are:

• test that waitUntil on load and DOMContentLoaded work as expected when used in goto.
• test that waitUntil on load, DOMContentLoaded and networkidle work as expected when we navigate to a page with a main and sub frame when used in goto.
• test that waitUntil on load, DOMContentLoaded and networkidle work as expected when used as an option on WaitForNavigation.
• test that waitUntil on networkidle timesout if we set it too late after the navigation has completed.

Linked issue: #593

[inancgumus]

Excellent work 👏 Thanks for considering my previous feedback and refactoring this 🙇

I'm approving this PR as it is, and I have some suggestions I want you to consider. All are optional. I believe there are some areas in which we can further decrease duplication and make it more straightforward and maintainable.

Commits:
IMHO, we don't need to make separate commits for minor changes, such as the following. Please consider squashing them

• Add general lifecycle event guidelines
• Rename the goto network lifecycle event tests
• Move general guideline comment to top
• Refactor ... test commits

It is now clear that the same code exercises the test cases of a table test. And each test case is small enough. A commit for each top-level test is enough. IMO, no need to make a commit for each table test. It is better to squash them into one commit.

The following static/*.html files are nearly identical.

• prolonged_network_idle.html
• prolonged_network_idle_10.html
• reload_lifecycle.html
• wait_for_nav_lifecycle.html

We can parameterize them for each test case instead of duplicating these files. You can use page.Eval to do that. I found that only the following parts change:

Changing parts:

+ <div id="pingJSText">Waiting...</div>
+ Loop count
+ <script src="/ping.js" async></script>
+ <a href="/home" id="homeLink">Home</a>

Summary :)
As the PR is big, I couldn't validate its functionality. I'll check it out once again when I'm back.

[ankur22]

Thanks for the suggestions! I'll take a look at them 🙂