DevTools: Fix live-edit.html test.

The failure happened because live-edit-no-reveal.html live edited the same script and this somehow
interfered with live-edit.html execution.

BUG=282082
TBR=pfeldman

Review URL: https://codereview.chromium.org/185683008

git-svn-id: svn://svn.chromium.org/blink/trunk@168609 bbb929c8-8fbe-4397-9dbb-9b2b20218538