[Runtime] Fix onLaunch event is not fired under service mode.

Bug reports 'webapi-runtime-xwalk-tests' cases are failed to launch.
Root cause is onLaunched event is not sent under run-as-service mode.
The patch fixed above issue.

BUG=XWALK-1228
Merge pull request #1738 from shaochangbin/fix-onlaunch

[Runtime] Fix onLaunch event is not fired under service mode.