Speedometer 2.0: Document es2015-babel-webpack build process

Speedometer 2.0: Document es2015-babel-webpack build process
https://bugs.webkit.org/show_bug.cgi?id=174252

Patch by Mathias Bynens <mathias@qiwi.be> on 2017-07-25
Reviewed by Ryosuke Niwa.

* Speedometer/resources/todomvc/vanilla-examples/es2015-babel-webpack/README.md: Added build docs.
* Speedometer/resources/todomvc/vanilla-examples/es2015-babel-webpack/dist/*: Update generated build files.
* Speedometer/resources/todomvc/vanilla-examples/es2015-babel-webpack/package.json: Remove unused items.
* Speedometer/resources/todomvc/vanilla-examples/es2015-babel-webpack/package-lock.json: Added lockfile.
* Speedometer/resources/todomvc/vanilla-examples/es2015-babel-webpack/src/index.html: Make title consistent.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@219903 268f45cc-cd09-0410-ab3c-d52691b4dbfc