IndexedDB: Drop database backend reference after connection is closed

R=dgrogan@chromium.org,alecflett@chromium.org,jamesr@chromium.org
BUG=261861

Review URL: https://chromiumcodereview.appspot.com/19678022

git-svn-id: svn://svn.chromium.org/blink/trunk@155095 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: beautify settings screen (equal line spacing and proper indentation)

BUG=263850

Review URL: https://chromiumcodereview.appspot.com/19812006

git-svn-id: svn://svn.chromium.org/blink/trunk@155096 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: [CodeMirror] LayoutTest to verify revealLine functionality

This patch adds layout test to verify revealLine functionality and
fixes minor bug, unveiled by this test.

BUG=

Review URL: https://chromiumcodereview.appspot.com/19872004

git-svn-id: svn://svn.chromium.org/blink/trunk@155097 bbb929c8-8fbe-4397-9dbb-9b2b20218538