Listen for input and change event to change color opacity value

The issue does arise due to change for slide change event changes in https://codereview.chromium.org/125973004/.

The issue is due to Spectrum.js is listening for change event and none gets fired after the above commit. As per spec (http://www.w3.org/TR/html5/forms.html#common-event-behaviors) for type range, input event should be firedi while dragging, while change event is fired when dragging is stopped. As values needs to be updated during drag, input event should also be listened.

Spectrum.js is updated to listen for both input and change event to resolve above issue.

R=tkent
BUG=337801
TEST=NONE

Review URL: https://codereview.chromium.org/143953014

git-svn-id: svn://svn.chromium.org/blink/trunk@166026 bbb929c8-8fbe-4397-9dbb-9b2b20218538