Cast highestEnclosingNodeOfType() return value to tighter type

Source/core/editing/htmlediting.h

 /*
  * Copyright (C) 2004, 2006, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 85 matching lines @@
 {
     return !node->isTextNode() && node->canContainRangeEndPoint();
 }
 
 bool isAtomicNode(const Node*);
 bool isBlock(const Node*);
 bool isInline(const Node*);
 bool isSpecialHTMLElement(const Node*);
 bool isTabSpanElement(const Node*);
 bool isTabSpanTextNode(const Node*);
-bool isMailBlockquote(const Node*);
+bool isMailHTMLBlockquoteElement(const Node*);
 bool isRenderedTable(const Node*);
 bool isRenderedTableElement(const Node*);
 bool isTableCell(const Node*);
 bool isEmptyTableCell(const Node*);
 bool isTableStructureNode(const Node*);
 bool isListElement(Node*);
 bool isListItem(const Node*);
 bool isNodeRendered(const Node*);
 bool isNodeVisiblyContainedWithin(Node&, const Range&);
 bool isRenderedAsNonInlineTableImageOrHR(const Node*);
@@ skipping 149 matching lines @@
     // FIXME: this is required until 6853027 is fixed and text checking can do this for us.
     return character == '\'' || character == rightSingleQuotationMark || character == hebrewPunctuationGershayim;
 }
 
 String stringWithRebalancedWhitespace(const String&, bool startIsStartOfParagraph, bool endIsEndOfParagraph);
 const String& nonBreakingSpaceString();
 
 }
 
 #endif