Web Inspector: Refactor InspectorDOMStorageAgent::getDOMStorageEntries to report the error messages
https://bugs.webkit.org/show_bug.cgi?id=108611

Reviewed by Pavel Feldman.

Added reporting of various error messages. Moved the modification of output
parameter at a later stage when there are no errors reported.

No new tests as code refactoring.

* inspector/InspectorDOMStorageAgent.cpp:
(WebCore::hadException):
(WebCore):
(WebCore::InspectorDOMStorageAgent::getDOMStorageEntries):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141690 268f45cc-cd09-0410-ab3c-d52691b4dbfc