DevTools: Make SourcesView shortcut work when it is shown in drawer and move "save" shortcut into it.

R=pfeldman@chromium.org, apavlov, lushnikov, pfeldman
BUG=322632, 349428

Review URL: https://codereview.chromium.org/212623013

git-svn-id: svn://svn.chromium.org/blink/trunk@170309 bbb929c8-8fbe-4397-9dbb-9b2b20218538