Make InlineBox::renderer() and related subclass methods return reference.

Source/core/rendering/svg/SVGInlineFlowBox.cpp

Index: Source/core/rendering/svg/SVGInlineFlowBox.cpp
diff --git a/Source/core/rendering/svg/SVGInlineFlowBox.cpp b/Source/core/rendering/svg/SVGInlineFlowBox.cpp
index 183291168e51e097584654995ab180c186c85637..d4a861c3db29e358defbcfc544c1080a0254b4df 100644
--- a/Source/core/rendering/svg/SVGInlineFlowBox.cpp
+++ b/Source/core/rendering/svg/SVGInlineFlowBox.cpp
@@ -50,10 +50,7 @@ void SVGInlineFlowBox::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffse
     ASSERT(paintInfo.phase == PaintPhaseForeground || paintInfo.phase == PaintPhaseSelection);
     ASSERT(!paintInfo.context->paintingDisabled());
 
-    RenderObject* boxRenderer = renderer();
-    ASSERT(boxRenderer);
-
-    SVGRenderingContext renderingContext(boxRenderer, paintInfo, SVGRenderingContext::SaveGraphicsContext);
+    SVGRenderingContext renderingContext(&renderer(), paintInfo, SVGRenderingContext::SaveGraphicsContext);
     if (renderingContext.isRenderingPrepared()) {
         for (InlineBox* child = firstChild(); child; child = child->nextOnLine())
             child->paint(paintInfo, paintOffset, 0, 0);