Add method for reset crossEventCallHandler

Add method for reset crossEventCallHandler

[Issue#] JIRA(#N_SE-20674)
[Problem] Event handler isn't called
[Cause] After add commit for enhancement launching time,
event handler doesn't work.
Root cause is that pipe in the event handler is copyed during forking.
This cause occurred that event sends to parent process(UI)
even event is created by child process.
[Solution] Add reset method for event handler.
This method will be used in the webkit bundle.
[SCMRequest] N/A

Change-Id: I3875ab86a841ea7b8074b8936845cbdf45b7adc1