Further purify DatabaseTracker to use SecurityOriginData instead of "a String"

        * WebCore.base.exp:
        * WebCore.xcodeproj/project.pbxproj:
        * WebCore.vcproj/WebCore.vcproj
        * WebCore.pro

        * platform/SecurityOriginData.cpp: Added.
        (WebCore::SecurityOriginData::SecurityOriginData): Add a constructor that takes a "stringIdentifier"-style string,
          since that form is what will be stored in the Databases.db on disk
        (WebCore::SecurityOriginData::stringIdentifier):
        * platform/SecurityOriginData.h:
        (WebCore::SecurityOriginData::protocol):
        (WebCore::SecurityOriginData::host):
        (WebCore::SecurityOriginData::port):

        * storage/DatabaseTracker.cpp:
        (WebCore::SecurityOriginDataHash::hash): Follow the pattern Darin set in FontCache.cpp to make a decent hash for
          a SecurityOriginData object
        (WebCore::SecurityOriginDataHash::equal):
        (WebCore::SecurityOriginDataTraits::deletedValue): "file::1" will never exist in normal operation
        (WebCore::SecurityOriginDataTraits::emptyValue): "file::2" will never exist in normal operation
        (WebCore::DatabaseTracker::fullPathForDatabase):
        (WebCore::DatabaseTracker::populateOrigins):
        (WebCore::DatabaseTracker::origins):
        (WebCore::DatabaseTracker::addDatabase):
        * storage/DatabaseTracker.h:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@27851 268f45cc-cd09-0410-ab3c-d52691b4dbfc