Introduce DEFINE_FONT_DATA_TYPE_CASTS, and use it

Source/platform/fonts/GlyphPageTreeNode.cpp

 /*
  * Copyright (C) 2006, 2007, 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
@@ skipping 189 matching lines @@
                 }
             }
 
             // Now that we have a buffer full of characters, we want to get back an array
             // of glyph indices.  This part involves calling into the platform-specific
             // routine of our glyph map for actually filling in the page with the glyphs.
             // Success is not guaranteed. For example, Times fails to fill page 260, giving glyph data
             // for only 128 out of 256 characters.
             bool haveGlyphs;
             if (!fontData->isSegmented()) {
-                m_page = GlyphPage::createForSingleFontData(this, static_cast<const SimpleFontData*>(fontData));
-                haveGlyphs = fill(m_page.get(), 0, GlyphPage::size, buffer, bufferLength, static_cast<const SimpleFontData*>(fontData));
+                m_page = GlyphPage::createForSingleFontData(this, toSimpleFontData(fontData));
+                haveGlyphs = fill(m_page.get(), 0, GlyphPage::size, buffer, bufferLength, toSimpleFontData(fontData));
             } else {
                 m_page = GlyphPage::createForMixedFontData(this);
                 haveGlyphs = false;
 
-                const SegmentedFontData* segmentedFontData = static_cast<const SegmentedFontData*>(fontData);
+                const SegmentedFontData* segmentedFontData = toSegmentedFontData(fontData);
                 for (int i = segmentedFontData->numRanges() - 1; i >= 0; i--) {
                     const FontDataRange& range = segmentedFontData->rangeAt(i);
                     // all this casting is to ensure all the parameters to min and max have the same type,
                     // to avoid ambiguous template parameter errors on Windows
                     int from = max(0, static_cast<int>(range.from()) - static_cast<int>(start));
                     int to = 1 + min(static_cast<int>(range.to()) - static_cast<int>(start), static_cast<int>(GlyphPage::size) - 1);
                     if (from >= static_cast<int>(GlyphPage::size) || to <= 0)
                         continue;
 
                     // If this is a custom font needs to be loaded, do not fill
@@ skipping 187 matching lines @@
         printf("\nPage %d:\n", it->key);
         showGlyphPageTree(it->key);
     }
 }
 
 void showGlyphPageTree(unsigned pageNumber)
 {
     WebCore::GlyphPageTreeNode::getRoot(pageNumber)->showSubtree();
 }
 #endif