Added SuspendableScriptExecutor::createAndRun to replace ctor+run

R=vsevik@chromium.org,aandrey@chromium.org,pfeldman@chromium.org

Review URL: https://codereview.chromium.org/649183010

git-svn-id: svn://svn.chromium.org/blink/trunk@184344 bbb929c8-8fbe-4397-9dbb-9b2b20218538