Introduce DEFINE_INLINE_BOX_TYPE_CASTS, and use it

Source/core/rendering/InlineTextBox.h

Index: Source/core/rendering/InlineTextBox.h
diff --git a/Source/core/rendering/InlineTextBox.h b/Source/core/rendering/InlineTextBox.h
index fcd133e01493dbfaba16d4b8f53e5c2560b30b83..86d4afb97de83545033c5a9b92e54bdaf1401456 100644
--- a/Source/core/rendering/InlineTextBox.h
+++ b/Source/core/rendering/InlineTextBox.h
@@ -190,20 +190,7 @@ private:
     }
 };
 
-inline InlineTextBox* toInlineTextBox(InlineBox* inlineBox)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!inlineBox || inlineBox->isInlineTextBox());
-    return static_cast<InlineTextBox*>(inlineBox);
-}
-
-inline const InlineTextBox* toInlineTextBox(const InlineBox* inlineBox)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!inlineBox || inlineBox->isInlineTextBox());
-    return static_cast<const InlineTextBox*>(inlineBox);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toInlineTextBox(const InlineTextBox*);
+DEFINE_INLINE_BOX_TYPE_CASTS(InlineTextBox);
 
 inline RenderText* InlineTextBox::textRenderer() const
 {