DevTools: Fix Ctrl+Shift shortcut handling
DevTools: Fix Ctrl+Shift shortcut handling

Drive-by: be more lenient when detecting printable key press combinations.

R=vsevik@chromium.org, vsevik
NOTRY=true

Review URL: https://codereview.chromium.org/244913002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@172024 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs