DevTools: Remove global dependencies on WebInspector.debuggerModel. BreakpointsSidebarPane

BUG=

Review URL: https://codereview.chromium.org/138913018

git-svn-id: svn://svn.chromium.org/blink/trunk@167018 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Don't use task modes for non-debugger tasks

BUG=301514
R=kinuko@chromium.org,tyoshino@chromium.org

Review URL: https://codereview.chromium.org/159843005

git-svn-id: svn://svn.chromium.org/blink/trunk@167019 bbb929c8-8fbe-4397-9dbb-9b2b20218538