DevTools: [CodeMirror] support multicursor actions in smartNewLineAndIndent

This patch fixes smartNewLineAndIndent command to support multicursor.
The block-indent-controller test was updated due to fix in editor-test.js and rebaselined to output "dots" instead of spaces for clarity.

Review URL: https://codereview.chromium.org/372763002

git-svn-id: svn://svn.chromium.org/blink/trunk@177655 bbb929c8-8fbe-4397-9dbb-9b2b20218538