Minimize RenderObject* casting to RenderText*

Source/core/rendering/RenderBlock.h

Index: Source/core/rendering/RenderBlock.h
diff --git a/Source/core/rendering/RenderBlock.h b/Source/core/rendering/RenderBlock.h
index 4e0ecb8ab1c5a7cbddbd7f2fe022f21013929daf..abf50ec73fbfd8767388df38c76399ee66da6718 100644
--- a/Source/core/rendering/RenderBlock.h
+++ b/Source/core/rendering/RenderBlock.h
@@ -37,14 +37,13 @@
 
 namespace blink {
 
+class LineInfo;
 class LineLayoutState;
-class RenderInline;
-
 struct PaintInfo;
-class WordMeasurement;
-
-class LineInfo;
+class RenderInline;
 class RenderRubyRun;
+class RenderText;
+class WordMeasurement;
 
 template <class Run> class BidiRunList;
 typedef WTF::ListHashSet<RenderBox*, 16> TrackedRendererListHashSet;
@@ -358,7 +357,7 @@ private:
     void insertIntoTrackedRendererMaps(RenderBox* descendant, TrackedDescendantsMap*&, TrackedContainerMap*&);
     static void removeFromTrackedRendererMaps(RenderBox* descendant, TrackedDescendantsMap*&, TrackedContainerMap*&);
 
-    void createFirstLetterRenderer(RenderObject* firstLetterBlock, RenderObject* currentChild, unsigned length);
+    void createFirstLetterRenderer(RenderObject* firstLetterBlock, RenderText& currentChild, unsigned length);
     void updateFirstLetterStyle(RenderObject* firstLetterBlock, RenderObject* firstLetterContainer);
 
     Node* nodeForHitTest() const;