DevTools: properly support targets in LiveEditSupport

BUG=

Review URL: https://codereview.chromium.org/352953002

git-svn-id: svn://svn.chromium.org/blink/trunk@177096 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Get rid of WebInspector.debuggerModel in NetworkUISourceCodeProvider

BUG=

Review URL: https://codereview.chromium.org/356033002

git-svn-id: svn://svn.chromium.org/blink/trunk@177097 bbb929c8-8fbe-4397-9dbb-9b2b20218538