DevTools: Merge highlightPosition and revealLine methods on SourceFrame.

This patch keeps highlightPosition method on SourceFrame for backwards compatibility with corresponding virtual methods on View.

R=lushnikov@chromium.org, lushnikov, pfeldman

Review URL: https://codereview.chromium.org/204323003

git-svn-id: svn://svn.chromium.org/blink/trunk@169551 bbb929c8-8fbe-4397-9dbb-9b2b20218538