--- a/dom/svg/SVGSVGElement.cpp
+++ b/dom/svg/SVGSVGElement.cpp
@@ -129,16 +129,20 @@ NS_INTERFACE_TABLE_HEAD_CYCLE_COLLECTION
 NS_INTERFACE_TABLE_TAIL_INHERITING(SVGSVGElementBase)
 
 //----------------------------------------------------------------------
 // Implementation
 
 SVGSVGElement::SVGSVGElement(already_AddRefed<mozilla::dom::NodeInfo>& aNodeInfo,
                              FromParser aFromParser)
   : SVGSVGElementBase(aNodeInfo),
+    mCurrentTranslate(0.0f, 0.0f),
+    mCurrentScale(1.0f),
+    mPreviousTranslate(0.0f, 0.0f),
+    mPreviousScale(1.0f),
     mStartAnimationOnBindToTree(aFromParser == NOT_FROM_PARSER ||
                                 aFromParser == FROM_PARSER_FRAGMENT ||
                                 aFromParser == FROM_PARSER_XSLT),
     mImageNeedsTransformInvalidation(false)
 {
 }
 
 SVGSVGElement::~SVGSVGElement()

--- a/dom/svg/SVGSVGElement.h
+++ b/dom/svg/SVGSVGElement.h
@@ -85,22 +85,16 @@ public:
    * For use by zoom controls to allow currentScale, currentTranslate.x and
    * currentTranslate.y to be set by a single operation that dispatches a
    * single SVGZoom event (instead of one SVGZoom and two SVGScroll events).
    *
    * XXX SVGZoomEvent is no more, is this needed?
    */
   void SetCurrentScaleTranslate(float s, float x, float y);
 
-  /**
-   * Retrieve the value of currentScale and currentTranslate.
-   */
-  const SVGPoint& GetCurrentTranslate() { return mCurrentTranslate; }
-  float GetCurrentScale() { return mCurrentScale; }
-
   // nsIContent interface
   virtual nsresult GetEventTargetParent(
                      EventChainPreVisitor& aVisitor) override;
 
   // nsINode methods:
   virtual nsresult Clone(mozilla::dom::NodeInfo *aNodeInfo, nsINode **aResult,
                          bool aPreallocateChildren) const override;
 
@@ -216,26 +210,39 @@ private:
   void ClearImageOverridePreserveAspectRatio();
 
   // Set/Clear properties to hold old version of preserveAspectRatio
   // when it's being overridden by an <image> element that we are inside of.
   bool SetPreserveAspectRatioProperty(const SVGPreserveAspectRatio& aPAR);
   const SVGPreserveAspectRatio* GetPreserveAspectRatioProperty() const;
   bool ClearPreserveAspectRatioProperty();
 
+  virtual SVGPoint GetCurrentTranslate() const override
+  { return mCurrentTranslate; }
+  virtual float GetCurrentScale() const override
+  { return mCurrentScale; }
+
   virtual EnumAttributesInfo GetEnumInfo() override;
 
   nsSVGEnum mEnumAttributes[1];
   static nsSVGEnumMapping sZoomAndPanMap[];
   static EnumInfo sEnumInfo[1];
 
   // The time container for animations within this SVG document fragment. Set
   // for all outermost <svg> elements (not nested <svg> elements).
   nsAutoPtr<nsSMILTimeContainer> mTimedDocumentRoot;
 
+  // zoom and pan
+  // IMPORTANT: see the comment in RecordCurrentScaleTranslate before writing
+  // code to change any of these!
+  SVGPoint mCurrentTranslate;
+  float    mCurrentScale;
+  SVGPoint mPreviousTranslate;
+  float    mPreviousScale;
+
   // For outermost <svg> elements created from parsing, animation is started by
   // the onload event in accordance with the SVG spec, but for <svg> elements
   // created by script or promoted from inner <svg> to outermost <svg> we need
   // to manually kick off animation when they are bound to the tree.
   bool     mStartAnimationOnBindToTree;
 
   bool     mImageNeedsTransformInvalidation;
 };

--- a/dom/svg/SVGViewportElement.cpp
+++ b/dom/svg/SVGViewportElement.cpp
@@ -55,20 +55,16 @@ SVGView::SVGView()
 
 //----------------------------------------------------------------------
 // Implementation
 
 SVGViewportElement::SVGViewportElement(already_AddRefed<mozilla::dom::NodeInfo>& aNodeInfo)
   : SVGGraphicsElement(aNodeInfo),
     mViewportWidth(0),
     mViewportHeight(0),
-    mCurrentTranslate(0.0f, 0.0f),
-    mCurrentScale(1.0f),
-    mPreviousTranslate(0.0f, 0.0f),
-    mPreviousScale(1.0f),
     mHasChildrenOnlyTransform(false)
 {
 }
 
 SVGViewportElement::~SVGViewportElement()
 {
 }
 
@@ -162,18 +158,18 @@ ComputeSynthesizedViewBoxDimension(const
 //----------------------------------------------------------------------
 // public helpers:
 
 void
 SVGViewportElement::UpdateHasChildrenOnlyTransform()
 {
   bool hasChildrenOnlyTransform =
     HasViewBoxOrSyntheticViewBox() ||
-    (IsRoot() && (mCurrentTranslate != SVGPoint(0.0f, 0.0f) ||
-                  mCurrentScale != 1.0f));
+    (IsRoot() && (GetCurrentTranslate() != SVGPoint(0.0f, 0.0f) ||
+                  GetCurrentScale() != 1.0f));
   mHasChildrenOnlyTransform = hasChildrenOnlyTransform;
 }
 
 void
 SVGViewportElement::ChildrenOnlyTransformChanged(uint32_t aFlags)
 {
   // Avoid wasteful calls:
   MOZ_ASSERT(!(GetPrimaryFrame()->GetStateBits() & NS_FRAME_IS_NONDISPLAY),
@@ -308,20 +304,22 @@ SVGViewportElement::PrependLocalTransfor
 
   gfxMatrix childToUser;
 
   if (IsInner()) {
     float x, y;
     const_cast<SVGViewportElement*>(this)->GetAnimatedLengthValues(&x, &y, nullptr);
     childToUser = ThebesMatrix(GetViewBoxTransform().PostTranslate(x, y));
   } else if (IsRoot()) {
+    SVGPoint translate = GetCurrentTranslate();
+    float scale = GetCurrentScale();
     childToUser = ThebesMatrix(GetViewBoxTransform()
-                                 .PostScale(mCurrentScale, mCurrentScale)
-                                 .PostTranslate(mCurrentTranslate.GetX(),
-                                                mCurrentTranslate.GetY()));
+                                 .PostScale(scale, scale)
+                                 .PostTranslate(translate.GetX(),
+                                                translate.GetY()));
   } else {
     // outer-<svg>, but inline in some other content:
     childToUser = ThebesMatrix(GetViewBoxTransform());
   }
 
   if (aWhich == eAllTransforms) {
     return childToUser * userToParent * aMatrix;
   }

--- a/dom/svg/SVGViewportElement.h
+++ b/dom/svg/SVGViewportElement.h
@@ -178,16 +178,24 @@ protected:
   /**
    * Returns the explicit viewBox rect, if specified, or else a synthesized
    * viewBox, if appropriate, or else a viewBox matching the dimensions of the
    * SVG viewport.
    */
   nsSVGViewBoxRect GetViewBoxWithSynthesis(
       float aViewportWidth, float aViewportHeight) const;
 
+  /**
+   * Retrieve the value of currentScale and currentTranslate.
+   */
+  virtual SVGPoint GetCurrentTranslate() const
+  { return SVGPoint(0.0f, 0.0f); }
+  virtual float GetCurrentScale() const
+  { return 1.0f; }
+
   enum { ATTR_X, ATTR_Y, ATTR_WIDTH, ATTR_HEIGHT };
   nsSVGLength2 mLengthAttributes[4];
   static LengthInfo sLengthInfo[4];
   virtual LengthAttributesInfo GetLengthInfo() override;
 
   enum { ZOOMANDPAN };
 
   virtual SVGAnimatedPreserveAspectRatio *GetPreserveAspectRatio() override;
@@ -205,24 +213,16 @@ protected:
   //
   //   http://www.w3.org/TR/SVG11/coords.html#ViewportSpace
   //
   // XXXjwatt Currently only used for outer <svg>, but maybe we could use -1 to
   // flag this as an inner <svg> to save the overhead of GetCtx calls?
   // XXXjwatt our frame should probably reset these when it's destroyed.
   float mViewportWidth, mViewportHeight;
 
-  // zoom and pan
-  // IMPORTANT: see the comment in RecordCurrentScaleTranslate before writing
-  // code to change any of these!
-  SVGPoint mCurrentTranslate;
-  float    mCurrentScale;
-  SVGPoint mPreviousTranslate;
-  float    mPreviousScale;
-
   bool     mHasChildrenOnlyTransform;
 };
 
 } // namespace dom
 
 } // namespace mozilla
 
 #endif // SVGViewportElement_h