DevTools: [CodeMirror] copy selection in readonly mode

This patch does a workaround for CodeMirror bug that prevents
it from handling copy command in "nocursor". This workaround
doesn't use the "nocursor" readonly mode, but uses plain "readonly"
and extends it with style class that hides cursor.

BUG=257081

Review URL: https://chromiumcodereview.appspot.com/18437003

git-svn-id: svn://svn.chromium.org/blink/trunk@153562 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: fix Ctrl-O dialog rendering glitch

This patch fixes a rendering glitch in Ctrl-O dialog which highlighted
wrong query in filtered items. This was caused by an outdated scoring
function which was used for item rendering.

BUG=257075

Review URL: https://chromiumcodereview.appspot.com/18083027

git-svn-id: svn://svn.chromium.org/blink/trunk@153564 bbb929c8-8fbe-4397-9dbb-9b2b20218538