[iOS] Update EditorIOS.mm to switch from pointers to references

[iOS] Update EditorIOS.mm to switch from pointers to references

* editing/ios/EditorIOS.mm:
(WebCore::Editor::setTextAlignmentForChangedBaseWritingDirection):
(WebCore::Editor::insertParagraphSeparatorInQuotedContent):
(WebCore::styleForSelectionStart):
(WebCore::Editor::selectionInWebArchiveFormat):
(WebCore::Editor::writeImageToPasteboard):
(WebCore::Editor::WebContentReader::readWebArchive):
(WebCore::Editor::WebContentReader::readRTFD):
(WebCore::Editor::WebContentReader::readRTF):
(WebCore::uniqueURLWithRelativePart):
(WebCore::Editor::WebContentReader::readPlainText):
(WebCore::Editor::webContentFromPasteboard):
(WebCore::Editor::createFragmentAndAddResources):
(WebCore::Editor::createFragmentForImageResourceAndAddResource):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@161735 268f45cc-cd09-0410-ab3c-d52691b4dbfc