Change DPL::WaitableHandleWatchSupport's destructor not to call DPL:Aassert explicitly.

Change DPL::WaitableHandleWatchSupport's destructor not to call DPL:Aassert explicitly.

[Issue#] N_SE-23934
[Problem] When chatter, SDK sample webapp, is closed, chatter's Web Process is asserted
[Cause] DPL::WaitableHandleWatchSupport's destructor call assert if its map container has any instance.
[Solution] DPL::WaitableHandleWatchSupport's destructor doesn't call assert function explicitly in any case.
           Even if its map container has any instance, destructor of map container releases existing instances in it automatically.

Change-Id: Ieb54e1b6a692132222e72e7b41f0666d4a211afa