DevTools: remove search highlight in console without rebuilding DOM

This patch removes search highlight in-place without rebuilding DOM and
thus wihtout loosing the expanded state of console view message.

BUG=397142
R=vsevik

Review URL: https://codereview.chromium.org/653853003

git-svn-id: svn://svn.chromium.org/blink/trunk@184051 bbb929c8-8fbe-4397-9dbb-9b2b20218538