Reviewed by Darin Fisher.

        Chromium needs to be able to override the way storage events are delivered
        https://bugs.webkit.org/show_bug.cgi?id=29655

        Chromium needs to be able to override the way storage events are delivered.
        This replaced https://bugs.webkit.org/show_bug.cgi?id=29257 because it'll be
        faster (no vtables and extra allocation) and somewhat cleaner (no dependency
        injection).  This is necessary because Chromium needs to transport events across
        a process barrier and then dispatch them without use of a Frame*.

        Behavior should not change with this, so no updates to tests.

        * GNUmakefile.am:
        * WebCore.gypi:
        * WebCore.vcproj/WebCore.vcproj:
        * WebCore.xcodeproj/project.pbxproj:
        * WebCoreSources.bkl:
        * storage/StorageAreaImpl.cpp:
        (WebCore::StorageAreaImpl::setItem):
        (WebCore::StorageAreaImpl::removeItem):
        (WebCore::StorageAreaImpl::clear):
        * storage/StorageAreaImpl.h:
        * storage/StorageEventDispatcher.cpp: Copied from WebCore/storage/StorageAreaImpl.cpp.
        (WebCore::StorageEventDispatcher::dispatch):
        * storage/StorageEventDispatcher.h: Added.  (Well, technically in the other half of this patch.)


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@48937 268f45cc-cd09-0410-ab3c-d52691b4dbfc