• Modified compositoin mode event handlers to provide better support for mobile browsers

• Added test cases for DraftEditorCompositionHandler

• Linter compliance

• Added support for compositionupdate event.

• Made the linter happy!

• Normalize beforeInput and compositionUpdate data

This continues from
facebookarchive#1152 and
facebookarchive#1285
making them work together for broad support for polatform
inconsistencies.

• Put new composition fixes behind a feature flag

• lint

• correct resets

• Fix Synthetic Event flow types

• Convert DraftEditorCompositionHandler tests to root tests + snapshots

• Remove unnecessary DraftFeatureFlags

Before submitting a pull request, please make sure the following is done...

1. Fork the repo and create your branch from master.
2. If you've added code that should be tested, add tests!
3. If you've changed APIs, update the documentation.
4. Ensure that:

• The test suite passes (npm test)
• Your code lints (npm run lint) and passes Flow (npm run flow)
• You have followed the testing guidelines

5. If you haven't already, complete the CLA.

Please use the simple form below as a guideline for describing your pull request.

Thanks for contributing to Draft.js!

Summary

[...]

Test Plan

[...]