[KeyEvent Mac] Remove the WebInputEventFactory from blink.

The code has migrated into the chromium code base. See 
change https://codereview.chromium.org/1331013004/ for the 
chromium side change.

Only Mac used the WebInputEventFactory; the rest of the 
platforms had their code converted into chromium long ago.

BUG=493833,237267

Review URL: https://codereview.chromium.org/1335673002

git-svn-id: svn://svn.chromium.org/blink/trunk/public@202454 bbb929c8-8fbe-4397-9dbb-9b2b20218538
2 files changed