DevTools: execute scripts in addScriptToEvaluateOnLoad in order

Scripts added by addScriptToEvaluateOnLoad used to be evaluated
in the order of their addition.

This was regressed recently with https://crrev.com/578514.

R=caseq, pfeldman

Change-Id: Ieabd67aca497fab8eaff749fea0877d93c54deae
Reviewed-on: https://chromium-review.googlesource.com/1180585
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Commit-Queue: Andrey Lushnikov <lushnikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584293}
4 files changed