Gardening: Platform-specific results for http/tests/xmlhttprequest/origin-exact-matching

For whatever reason, 10.9/10.6 behave differently than 10.8/10.7 when
presented with '\0' in HTTP headers. Hooray.

BUG=344294
TBR=dstockwell@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/170263004

git-svn-id: svn://svn.chromium.org/blink/trunk@167326 bbb929c8-8fbe-4397-9dbb-9b2b20218538