Chinese punctuation added with Sogou Wubi disappears in Win7/IE11

[robbertbrak]

Do you want to request a feature or report a bug?

Report a bug.

What is the current behavior?

When you enter (full-width) Chinese punctuation with Sogou Wubi IME on Win7/IE11, it disappears as soon as React/Draft rerenders the block, for example when you press backspace.

**If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem.

To reproduce:

• Go to http://facebook.github.io/draft-js/ or the rich text example on Win7/IE11.
• Switch to Sogou Wubi IME and start typing Chinese.
• Type several punctuation marks, such as dots, question marks, comma's, spaces or numbers.
• Type backspace (or do something else that rerenders the block).
• Result: all the punctuation marks disappear.

See screencast below.

What is the expected behavior?

The punctuation marks apparently do not get registered in the internal editor representation. It seems that entering punctuation with Sogou Wubi does not fire the input event, nor does it fire oncompositionstart. The keydown and keyup events do get fired, though.

I'd like to help to fix this, but I could use some pointers on how to get started.

Which versions of Draft.js, and which browser / OS are affected by this issue? Did this work in previous versions of Draft.js?

Affects all versions of Draft on Win7/IE11. Note that it doesn't work on Facebook.com either, so this must be a known issue?

[robbertbrak]

I think this might be related to #693 and facebook/react#7107. @spicyj, since you were involved in that pull request, would you care to comment? Should we somehow make the beforeInput event fire in the described situation?