Replace static_cast with safe casting methods

Source/core/editing/markup.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009, 2010, 2011 Google Inc. All rights reserved.
  * Copyright (C) 2011 Igalia S.L.
  * Copyright (C) 2011 Motorola Mobility. 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
@@ skipping 445 matching lines @@
 
 static bool propertyMissingOrEqualToNone(StylePropertySet* style, CSSPropertyID propertyID)
 {
     if (!style)
         return false;
     RefPtr<CSSValue> value = style->getPropertyCSSValue(propertyID);
     if (!value)
         return true;
     if (!value->isPrimitiveValue())
         return false;
-    return static_cast<CSSPrimitiveValue*>(value.get())->getValueID() == CSSValueNone;
+    return toCSSPrimitiveValue(value.get())->getValueID() == CSSValueNone;
 }
 
 static bool needInterchangeNewlineAfter(const VisiblePosition& v)
 {
     VisiblePosition next = v.next();
     Node* upstreamNode = next.deepEquivalent().upstream().deprecatedNode();
     Node* downstreamNode = v.deepEquivalent().downstream().deprecatedNode();
     // Add an interchange newline if a paragraph break is selected and a br won't already be added to the markup to represent it.
     return isEndOfParagraph(v) && isStartOfParagraph(next) && !(upstreamNode->hasTagName(brTag) && upstreamNode == downstreamNode);
 }
@@ skipping 606 matching lines @@
     if (hasOneChild(containerNode.get())) {
         containerNode->replaceChild(textNode.release(), containerNode->firstChild(), es);
         return;
     }
 
     containerNode->removeChildren();
     containerNode->appendChild(textNode.release(), es);
 }
 
 }