DevTools: Show unicode "hair space" as html entity in Dev Tools Elements Panel

The DOM tree should show &#8202; instead of an ordinary space
for the Hairspace (\u200a) character.

BUG=232970

Review URL: https://codereview.chromium.org/14236007

git-svn-id: svn://svn.chromium.org/blink/trunk@148638 bbb929c8-8fbe-4397-9dbb-9b2b20218538