IE11 fix for range input not updating

[jwijay]

What does this PR do?

adds this._onChangeRange to onMouseUp React event for range input example.

What testing has been done on this PR?

Range input in grommet-docs Form example has been tested in IE11, Chrome, Safari, and Firefox.

What are the relevant issues?

grommet/grommet#241

It looks like React v15 has a known issue with updating range inputs in IE11 using the React onChange event.

• See here for demo (vanilla JS onchange event firing correctly vs. React onChange event not firing when attached to a range input in IE11): https://jsfiddle.net/m78g29m5/
• Relevant Github issue: onChange doesn't work on IE for type=range facebook/react#3096 (comment)
• Proposed workaround (using onMouseUp in addition to onChange): input type=range onChange should fire when changing the value using the keyboard arrow keys facebook/react#554 (comment)

Attaching the _onChangeRange function to the range input's onMouseUp event (in addition to the onChange event) appears to fix the issue for IE11.

Screenshots (if appropriate)

IE11 before fix:

IE11 after fix:

[alansouzati]

thanks for your investigation.

[soulprovidr]

(Just wanted to say thanks, I was able to solve our IE11 range slider issues due to this thread).