Updated webplatform Drag event reference url
Update flexbox.json

Status: RESOLVED FIXED
https://bugzilla.mozilla.org/show_bug.cgi?id=702508
Features supported by Firefox 28
data update
Merge pull request #395 from sladex/patch-2

Update flexbox.json
Merge pull request #396 from mpopp75/fx28

Features supported by Firefox 28
Merge pull request #388 from pierceray/drag-urlupdate

Updated webplatform drag event reference url
data update