diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index 19565f00b378..929a2d84e84f 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -369,22 +369,18 @@ static inline nscoord ScaleViewportCoordTrunc(const nsCSSValue& aValue,
                                aViewportSize / 100.0f);
 }
 
+/* static */
 already_AddRefed<nsFontMetrics>
-GetMetricsFor(nsPresContext* aPresContext,
-              nsStyleContext* aStyleContext,
-              const nsStyleFont* aStyleFont,
-              nscoord aFontSize, // overrides value from aStyleFont
-              bool aUseUserFontSet)
+nsRuleNode::GetMetricsFor(nsPresContext* aPresContext,
+                          bool aIsVertical,
+                          const nsStyleFont* aStyleFont,
+                          nscoord aFontSize,
+                          bool aUseUserFontSet)
 {
   nsFont font = aStyleFont->mFont;
   font.size = aFontSize;
-  gfxFont::Orientation orientation = gfxFont::eHorizontal;
-  if (aStyleContext) {
-    WritingMode wm(aStyleContext);
-    if (wm.IsVertical() && !wm.IsSideways()) {
-      orientation = gfxFont::eVertical;
-    }
-  }
+  gfxFont::Orientation orientation
+    = aIsVertical ? gfxFont::eVertical : gfxFont::eHorizontal;
   nsFontMetrics::Params params;
   params.language = aStyleFont->mLanguage;
   params.explicitLanguage = aStyleFont->mExplicitLanguage;
@@ -395,6 +391,25 @@ GetMetricsFor(nsPresContext* aPresContext,
   return aPresContext->DeviceContext()->GetMetricsFor(font, params);
 }
 
+/* static */
+already_AddRefed<nsFontMetrics>
+nsRuleNode::GetMetricsFor(nsPresContext* aPresContext,
+                          nsStyleContext* aStyleContext,
+                          const nsStyleFont* aStyleFont,
+                          nscoord aFontSize, // overrides value from aStyleFont
+                          bool aUseUserFontSet)
+{
+  bool isVertical = false;
+  if (aStyleContext) {
+    WritingMode wm(aStyleContext);
+    if (wm.IsVertical() && !wm.IsSideways()) {
+      isVertical = true;
+    }
+  }
+  return nsRuleNode::GetMetricsFor(aPresContext, isVertical, aStyleFont,
+                                   aFontSize, aUseUserFontSet);
+}
+
 
 static nsSize CalcViewportUnitsScale(nsPresContext* aPresContext)
 {
diff --git a/layout/style/nsRuleNode.h b/layout/style/nsRuleNode.h
index f4755558058b..56faf5d62560 100644
--- a/layout/style/nsRuleNode.h
+++ b/layout/style/nsRuleNode.h
@@ -22,6 +22,7 @@
 
 class nsCSSPropertyIDSet;
 class nsCSSValue;
+class nsFontMetrics;
 class nsIStyleRule;
 class nsStyleContext;
 class nsStyleCoord;
@@ -797,6 +798,18 @@ public:
                                  bool aConvertListItem = false);
   static void EnsureInlineDisplay(mozilla::StyleDisplay& display);
 
+  static already_AddRefed<nsFontMetrics> GetMetricsFor(nsPresContext* aPresContext,
+                                                       bool aIsVertical,
+                                                       const nsStyleFont* aStyleFont,
+                                                       nscoord aFontSize,
+                                                       bool aUseUserFontSet);
+
+  static already_AddRefed<nsFontMetrics> GetMetricsFor(nsPresContext* aPresContext,
+                                                       nsStyleContext* aStyleContext,
+                                                       const nsStyleFont* aStyleFont,
+                                                       nscoord aFontSize,
+                                                       bool aUseUserFontSet);
+
   // Transition never returns null; on out of memory it'll just return |this|.
   nsRuleNode* Transition(nsIStyleRule* aRule, mozilla::SheetType aLevel,
                          bool aIsImportantRule);