Convert layer-related tests in fast/multicol to ref-tests.

layers-split-across-columns:

 * Use standards mode, not quirks mode.
 * Remove unnecessary uses of inline-block. (Abs. position instead).
 * Make things smaller, such that the entire test actually
   fits in the standard content_shell dimensions.

layers-in-multicol:

 * Standards mode.
 * Rewrote test to fit in content_shell.

Finally, removed related useless test-cases in fast/multicol/newmulticol.

R=mstensho@opera.com
BUG=380217

Review URL: https://codereview.chromium.org/615573003

git-svn-id: svn://svn.chromium.org/blink/trunk@183198 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: migrate extensible tabbed pane to promise-based instantiation.

Review URL: https://codereview.chromium.org/627653002

git-svn-id: svn://svn.chromium.org/blink/trunk@183199 bbb929c8-8fbe-4397-9dbb-9b2b20218538