WATCHLISTS: tyoshino watches fetch, loader, xmlhttprequest

R=yhirano
NOTRY=true
BUG=none

Review URL: https://codereview.chromium.org/681723002

git-svn-id: svn://svn.chromium.org/blink/trunk@184430 bbb929c8-8fbe-4397-9dbb-9b2b20218538