When accessing line boxes, use RenderBlockFlow instead of RenderBlock.

Source/core/rendering/RenderBlockFlow.h

Index: Source/core/rendering/RenderBlockFlow.h
diff --git a/Source/core/rendering/RenderBlockFlow.h b/Source/core/rendering/RenderBlockFlow.h
index 71be858e4a55902c2e011c35bc1d9da3170707af..1f29a4712e63132ab7cd3e4fd91d97bd2e4260b0 100644
--- a/Source/core/rendering/RenderBlockFlow.h
+++ b/Source/core/rendering/RenderBlockFlow.h
@@ -86,6 +86,14 @@ public:
             : logicalWidth() - logicalRightOffsetForLine(position, shouldIndentText, logicalHeight);
     }
 
+    // FIXME-BLOCKFLOW: Move this into RenderBlockFlow once there are no calls

[Julien - ping for review, 2014/07/18 21:10:50]

I think we should tie that to a bug if we have one.

+    // in RenderBlock.
+    using RenderBlock::lineBoxes;
+    using RenderBlock::firstLineBox;
+    using RenderBlock::lastLineBox;
+    using RenderBlock::firstRootBox;
+    using RenderBlock::lastRootBox;
+
     virtual LayoutUnit logicalLeftSelectionOffset(RenderBlock* rootBlock, LayoutUnit position) OVERRIDE;
     virtual LayoutUnit logicalRightSelectionOffset(RenderBlock* rootBlock, LayoutUnit position) OVERRIDE;