DevTools: [CodeMirror] indent auto-detection option

This patch adds "auto-detect" option into "indent" setting for
editor. This option will analyze given text and try to setup
a desired indentation level based on the content indentation.

BUG=
R=apavlov@chromium.org

Review URL: https://codereview.chromium.org/18768003

git-svn-id: svn://svn.chromium.org/blink/trunk@153762 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Move ImageStyle helpers to ElementStyleResources.

Yet more methods to shave off the inimitable StyleResolver. These
helpers work closely with the pending resources cache that
ElementStyleResources now manages. So we move these helpers there.

R=eae, eseidel
BUG=237268

Review URL: https://chromiumcodereview.appspot.com/18147016

git-svn-id: svn://svn.chromium.org/blink/trunk@153763 bbb929c8-8fbe-4397-9dbb-9b2b20218538
StyleSheet.ownerNode should be null when it gets orphaned.

Orphan StyleSheet objects shouldn't pointe their ex-ownerNode.
This change clears it when the owner detach such sheet objects.

TEST=discarded-sheet-owner-null.html
BUG=246203
R=haraken

Review URL: https://chromiumcodereview.appspot.com/18854017

git-svn-id: svn://svn.chromium.org/blink/trunk@153764 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[DevTools] Update search highlight style. EOM

Review URL: https://chromiumcodereview.appspot.com/18599004

git-svn-id: svn://svn.chromium.org/blink/trunk@153765 bbb929c8-8fbe-4397-9dbb-9b2b20218538