DevTools: Follow up fix for debugger-save-to-temp-var.html

BUG=427628
TBR=vsevik
NOTRY=true

Review URL: https://codereview.chromium.org/683793002

git-svn-id: svn://svn.chromium.org/blink/trunk@184500 bbb929c8-8fbe-4397-9dbb-9b2b20218538