Add a preliminary UA mapping for iOS 9
Add a preliminary UA mapping for iOS 9

Also removes obsolete iOS 6 entry.

BUG=None

Review URL: https://codereview.chromium.org/1315403004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#347445}

Chilledheart/chromium,Chilledheart/chromium,Chilledheart/chromium,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,Chilledheart/chromium,Chilledheart/chromium,axinging/chromium-crosswalk,Chilledheart/chromium,axinging/chromium-crosswalk,axinging/chromium-crosswalk,Chilledheart/chromium,Chilledheart/chromium,axinging/chromium-crosswalk,Chilledheart/chromium,axinging/chromium-crosswalk