Remove unreferences files from Source/core/Resources

The files deleted here are referenced in neither the Blink nor Chromium
source trees. The remaining image files in this directory are exported
by blink_resources.grd and consumed by webcursor_mac.mm in Chromium.

R=abarth@chromium.org, abarth

Review URL: https://codereview.chromium.org/25786002

git-svn-id: svn://svn.chromium.org/blink/trunk@158750 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add Source/platform/OWNERS.

Initially we add:
 - public/platform owners
 - Core owners in top 25 Source/core/platform contributors [1]

[1] http://blink.lc/blink/stats/Source/core/platform?period=q&ofs=25

BUG=297477
NOTRY=true

Review URL: https://codereview.chromium.org/25660002

git-svn-id: svn://svn.chromium.org/blink/trunk@158751 bbb929c8-8fbe-4397-9dbb-9b2b20218538