Make ct-popout-iframe size better.

Make the iframe inside the ct-popout-iframe fill it's container. That
way the embedder of the ct-popout-iframe gets to choose the size of
the iframe.

This also fixes the examine page for trooper failures to show a full
window iframe instead of a 400px one.

TBR since this is just changing styling.

TBR=rsesek@chromium.org

Review URL: https://codereview.chromium.org/629063002

git-svn-id: svn://svn.chromium.org/blink/trunk@183240 bbb929c8-8fbe-4397-9dbb-9b2b20218538