DevTools: REGRESSION: Profile start button is seen disabled.

BUG=369912
R=pfeldman, yurys

Review URL: https://codereview.chromium.org/273593003

git-svn-id: svn://svn.chromium.org/blink/trunk@173538 bbb929c8-8fbe-4397-9dbb-9b2b20218538