Remove unused files.

MSVC2013 ships with these headers, so there's no need to have local copies
of them anymore.

BUG=none

Review URL: https://codereview.chromium.org/596473003

git-svn-id: svn://svn.chromium.org/blink/trunk@182457 bbb929c8-8fbe-4397-9dbb-9b2b20218538