Constify metrics list references in SVGTextLayoutEngine

Source/core/rendering/svg/SVGTextLayoutEngine.h

Index: Source/core/rendering/svg/SVGTextLayoutEngine.h
diff --git a/Source/core/rendering/svg/SVGTextLayoutEngine.h b/Source/core/rendering/svg/SVGTextLayoutEngine.h
index 37de64d37e68d9436b4f856eb31eb93746944d12..2313753cd37162396e56f669921d2f3c2bad0a10 100644
--- a/Source/core/rendering/svg/SVGTextLayoutEngine.h
+++ b/Source/core/rendering/svg/SVGTextLayoutEngine.h
@@ -60,7 +60,7 @@ private:
     void updateCurrentTextPosition(float x, float y, float glyphAdvance);
     void updateRelativePositionAdjustmentsIfNeeded(float dx, float dy);
 
-    void recordTextFragment(SVGInlineTextBox*, Vector<SVGTextMetrics>&);
+    void recordTextFragment(SVGInlineTextBox*, const Vector<SVGTextMetrics>&);
     bool parentDefinesTextLength(RenderObject*) const;
 
     void layoutTextOnLineOrPath(SVGInlineTextBox*, RenderSVGInlineText*, const RenderStyle*);
@@ -68,7 +68,7 @@ private:
 
     bool currentLogicalCharacterAttributes(SVGTextLayoutAttributes*&);
     bool currentLogicalCharacterMetrics(SVGTextLayoutAttributes*&, SVGTextMetrics&);
-    bool currentVisualCharacterMetrics(SVGInlineTextBox*, Vector<SVGTextMetrics>&, SVGTextMetrics&);
+    bool currentVisualCharacterMetrics(SVGInlineTextBox*, const Vector<SVGTextMetrics>&, SVGTextMetrics&);
 
     void advanceToNextLogicalCharacter(const SVGTextMetrics&);
     void advanceToNextVisualCharacter(const SVGTextMetrics&);