Always use URL from EvaluateScript event payload when formatting it in Timeline

The url can never come from _initiator field in case of EvaluateScript event.

BUG=None
R=loislo@chromium.org

Review URL: https://codereview.chromium.org/299663004

git-svn-id: svn://svn.chromium.org/blink/trunk@174375 bbb929c8-8fbe-4397-9dbb-9b2b20218538