Try to rewrite e2e tests using jest-puppeter preset (#8301)

* Try to rewrite e2e tests using jest-puppeter preset

* Testing: Unskip NUX tests

* Testing: Unskip 4 more e2e tests

* Testsing: Unskip all e2e tests

* Tests: Add one more check for undo e2e tests

* Testing: Improve preview e2e test

* Tests: Use explicit `setViewport` calls

* Build: Ensure `npm run build` is always executed before e2e tests

* Tests: Change the trigger wchich finishes after test cleanup

* Stop using `targetcreated`, see berstend/puppeteer-extra#6

* lint fix

* Use `waitFor` instead of custom sleep

* Fix conflicts with master

* Lint fixes

* Update comment on race condition workaround

* Tests: Improve lifecycle methods for e2e setup

* Send more mousemove events, wait for selector before clicking

* chore: Improve variable name

* chore: Add colon to "See" comment

* chore: Tweak comments in undo test

* chore: Move puppeteer config to e2e folder

* chore: Introduce new e2e helper for clicking block appender

* Tests: Improve stability of e2e tests

* tests: Make e2e tests work with the lastest master changes

* tests: Add puppeteer config back

.travis.yml

@@ -63,5 +63,4 @@ jobs:
       env: WP_VERSION=latest
       script:
         - npm install || exit 1
-        - npm run build || exit 1
         - ./bin/run-e2e-tests.sh || exit 1