Reviewed by Kent Tamura.

        Spellcheck feature specific symbols should be defined.
        https://bugs.webkit.org/show_bug.cgi?id=56818

        * Introduced USE(UNIFIED_TEXT_CHECKING), USE(GRAMMAR_CHECKING) and USE(AUTOMATIC_TEXT_REPLACEMENT)
        * Replaced a part of of BUILDING_ON_* conditionals with them.

        Note that small amount of code path on Editor.cpp is now compiled under USE(GRAMMAR_CHECKING)
        because these code path is already built under non-Mac ports and
        Keeping them buildable for such platforms reduces the build breakage risk.
        These path is guarded by Settings thus should never get reached.

        No new tests. No behavioral change.

        * WebCore.gypi:
        * WebCore.pro:
        * WebCore.vcproj/WebCore.vcproj:
        * WebCore.xcodeproj/project.pbxproj:
        * editing/Editor.cpp:
        (WebCore::Editor::advanceToNextMisspelling):
        (WebCore::Editor::isSelectionUngrammatical):
        (WebCore::Editor::guessesForUngrammaticalSelection):
        (WebCore::Editor::guessesForMisspelledOrUngrammaticalSelection):
        (WebCore::Editor::markMisspellingsAfterTypingToWord):
        (WebCore::Editor::markMisspellingsOrBadGrammar):
        (WebCore::Editor::markBadGrammar):
        (WebCore::Editor::markAllMisspellingsAndBadGrammarInRanges):
        (WebCore::Editor::changeBackToReplacedString):
        (WebCore::Editor::markMisspellingsAndBadGrammar):
        * editing/Editor.h:
        * editing/TextCheckingHelper.cpp:
        (WebCore::TextCheckingHelper::findFirstMisspellingOrBadGrammar):
        (WebCore::TextCheckingHelper::findFirstGrammarDetail):
        (WebCore::TextCheckingHelper::findFirstBadGrammar):
        (WebCore::TextCheckingHelper::isUngrammatical):
        (WebCore::TextCheckingHelper::guessesForMisspelledOrUngrammaticalRange):
        (WebCore::TextCheckingHelper::markAllBadGrammar):
        * loader/EmptyClients.h:
        * platform/text/TextCheckerClient.h:
        * platform/text/TextChecking.h: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@81855 268f45cc-cd09-0410-ab3c-d52691b4dbfc