--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -2101,19 +2101,19 @@ const KTableEntry nsCSSProps::kTouchActi
 
 const KTableEntry nsCSSProps::kTopLayerKTable[] = {
   { eCSSKeyword_none,     NS_STYLE_TOP_LAYER_NONE },
   { eCSSKeyword_top,      NS_STYLE_TOP_LAYER_TOP },
   { eCSSKeyword_UNKNOWN, -1 }
 };
 
 const KTableEntry nsCSSProps::kTransformBoxKTable[] = {
-  { eCSSKeyword_border_box, NS_STYLE_TRANSFORM_BOX_BORDER_BOX },
-  { eCSSKeyword_fill_box, NS_STYLE_TRANSFORM_BOX_FILL_BOX },
-  { eCSSKeyword_view_box, NS_STYLE_TRANSFORM_BOX_VIEW_BOX },
+  { eCSSKeyword_border_box, StyleGeometryBox::Border },
+  { eCSSKeyword_fill_box, StyleGeometryBox::Fill },
+  { eCSSKeyword_view_box, StyleGeometryBox::View },
   { eCSSKeyword_UNKNOWN, -1 }
 };
 
 const KTableEntry nsCSSProps::kTransitionTimingFunctionKTable[] = {
   { eCSSKeyword_ease, NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE },
   { eCSSKeyword_linear, NS_STYLE_TRANSITION_TIMING_FUNCTION_LINEAR },
   { eCSSKeyword_ease_in, NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE_IN },
   { eCSSKeyword_ease_out, NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE_OUT },

--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -1451,16 +1451,17 @@ struct SetEnumValueHelper
   DEFINE_ENUM_CLASS_SETTER(StyleHyphens, None, Auto)
   DEFINE_ENUM_CLASS_SETTER(StyleTextJustify, None, InterCharacter)
   DEFINE_ENUM_CLASS_SETTER(StyleUserFocus, None, SelectMenu)
   DEFINE_ENUM_CLASS_SETTER(StyleUserSelect, None, MozText)
   DEFINE_ENUM_CLASS_SETTER(StyleUserInput, None, Auto)
   DEFINE_ENUM_CLASS_SETTER(StyleUserModify, ReadOnly, WriteOnly)
   DEFINE_ENUM_CLASS_SETTER(StyleWindowDragging, Default, NoDrag)
   DEFINE_ENUM_CLASS_SETTER(StyleOrient, Inline, Vertical)
+  DEFINE_ENUM_CLASS_SETTER(StyleGeometryBox, Border, View)
 #ifdef MOZ_XUL
   DEFINE_ENUM_CLASS_SETTER(StyleDisplay, None, MozPopup)
 #else
   DEFINE_ENUM_CLASS_SETTER(StyleDisplay, None, InlineBox)
 #endif
 
 #undef DEF_SET_ENUMERATED_VALUE
 };
@@ -6609,17 +6610,17 @@ nsRuleNode::ComputeDisplayData(void* aSt
            parentDisplay->mTransformStyle,
            NS_STYLE_TRANSFORM_STYLE_FLAT);
 
   // transform-box: enum, inherit, initial
   SetValue(*aRuleData->ValueForTransformBox(),
            display->mTransformBox, conditions,
            SETVAL_ENUMERATED | SETVAL_UNSET_INITIAL,
            parentDisplay->mTransformBox,
-           NS_STYLE_TRANSFORM_BOX_BORDER_BOX);
+           StyleGeometryBox::Border);
 
   // orient: enum, inherit, initial
   SetValue(*aRuleData->ValueForOrient(),
            display->mOrient, conditions,
            SETVAL_ENUMERATED | SETVAL_UNSET_INITIAL,
            parentDisplay->mOrient,
            StyleOrient::Inline);
 

--- a/layout/style/nsStyleConsts.h
+++ b/layout/style/nsStyleConsts.h
@@ -79,29 +79,29 @@ enum class StyleClear : uint8_t {
   InlineEnd,
   Both,
   // StyleClear::Line can be added to one of the other values in layout
   // so it needs to use a bit value that none of the other values can have.
   Line = 8,
   Max = 13  // Max = (Both | Line)
 };
 
-// Define geometry box for clip-path's reference-box, shape-outside's shape
-// box, background-clip, background-origin, mask-clip and mask-origin.
+// Define geometry box for clip-path's reference-box, background-clip,
+// background-origin, mask-clip, mask-origin, shape-box and transform-box.
 enum class StyleGeometryBox : uint8_t {
-  Content,
-  Padding,
+  Content, // Used by everything, except transform-box.
+  Padding, // Used by everything, except transform-box.
   Border,
   Margin,  // XXX Bug 1260094 comment 9.
            // Although margin-box is required by mask-origin and mask-clip, we
            // do not implement that due to lack of support in other browsers.
            // clip-path reference-box only.
-  Fill,    // mask-clip, mask-origin and clip-path reference-box only.
+  Fill,    // Used by everything, except shape-box.
   Stroke,  // mask-clip, mask-origin and clip-path reference-box only.
-  View,    // mask-clip, mask-origin and clip-path reference-box only.
+  View,    // Used by everything, except shape-box.
   NoClip,  // mask-clip only.
   Text,    // background-clip only.
   NoBox,   // Depending on which kind of element this style value applied on,
            // the default value of a reference-box can be different.
            // For an HTML element, the default value of reference-box is
            // border-box; for an SVG element, the default value is fill-box.
            // Since we can not determine the default value at parsing time,
            // set it as NoBox so that we make a decision later.
@@ -894,21 +894,16 @@ enum class StyleGridTrackBreadth : uint8
 #define NS_STYLE_TOUCH_ACTION_PAN_Y           (1 << 3)
 #define NS_STYLE_TOUCH_ACTION_MANIPULATION    (1 << 4)
 
 // See nsStyleDisplay
 #define NS_STYLE_TOP_LAYER_NONE   0 // not in the top layer
 #define NS_STYLE_TOP_LAYER_TOP    1 // in the top layer
 
 // See nsStyleDisplay
-#define NS_STYLE_TRANSFORM_BOX_BORDER_BOX                0
-#define NS_STYLE_TRANSFORM_BOX_FILL_BOX                  1
-#define NS_STYLE_TRANSFORM_BOX_VIEW_BOX                  2
-
-// See nsStyleDisplay
 #define NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE         0
 #define NS_STYLE_TRANSITION_TIMING_FUNCTION_LINEAR       1
 #define NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE_IN      2
 #define NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE_OUT     3
 #define NS_STYLE_TRANSITION_TIMING_FUNCTION_EASE_IN_OUT  4
 #define NS_STYLE_TRANSITION_TIMING_FUNCTION_STEP_START   5
 #define NS_STYLE_TRANSITION_TIMING_FUNCTION_STEP_END     6
 

--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -3264,17 +3264,17 @@ nsStyleDisplay::nsStyleDisplay(const nsP
   , mTouchAction(NS_STYLE_TOUCH_ACTION_AUTO)
   , mScrollBehavior(NS_STYLE_SCROLL_BEHAVIOR_AUTO)
   , mScrollSnapTypeX(NS_STYLE_SCROLL_SNAP_TYPE_NONE)
   , mScrollSnapTypeY(NS_STYLE_SCROLL_SNAP_TYPE_NONE)
   , mScrollSnapPointsX(eStyleUnit_None)
   , mScrollSnapPointsY(eStyleUnit_None)
   , mBackfaceVisibility(NS_STYLE_BACKFACE_VISIBILITY_VISIBLE)
   , mTransformStyle(NS_STYLE_TRANSFORM_STYLE_FLAT)
-  , mTransformBox(NS_STYLE_TRANSFORM_BOX_BORDER_BOX)
+  , mTransformBox(StyleGeometryBox::Border)
   , mSpecifiedTransform(nullptr)
   , mTransformOrigin{ {0.5f, eStyleUnit_Percent}, // Transform is centered on origin
                       {0.5f, eStyleUnit_Percent},
                       {0, nsStyleCoord::CoordConstructor} }
   , mChildPerspective(eStyleUnit_None)
   , mPerspectiveOrigin{ {0.5f, eStyleUnit_Percent},
                         {0.5f, eStyleUnit_Percent} }
   , mVerticalAlign(NS_STYLE_VERTICAL_ALIGN_BASELINE, eStyleUnit_Enumerated)

--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -2742,16 +2742,18 @@ private:
   StyleShapeSourceType mType = StyleShapeSourceType::None;
   StyleGeometryBox mReferenceBox = StyleGeometryBox::NoBox;
 };
 
 } // namespace mozilla
 
 struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleDisplay
 {
+  typedef mozilla::StyleGeometryBox StyleGeometryBox;
+
   explicit nsStyleDisplay(const nsPresContext* aContext);
   nsStyleDisplay(const nsStyleDisplay& aOther);
   ~nsStyleDisplay();
 
   void FinishStyle(nsPresContext* aPresContext) {}
 
   void* operator new(size_t sz, nsStyleDisplay* aSelf) { return aSelf; }
   void* operator new(size_t sz, nsPresContext* aContext) {
@@ -2830,17 +2832,17 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsSt
   nsTArray<mozilla::Position> mScrollSnapCoordinate; // [reset]
 
   // mSpecifiedTransform is the list of transform functions as
   // specified, or null to indicate there is no transform.  (inherit or
   // initial are replaced by an actual list of transform functions, or
   // null, as appropriate.)
   uint8_t mBackfaceVisibility;
   uint8_t mTransformStyle;
-  uint8_t mTransformBox;        // [reset] see nsStyleConsts.h
+  StyleGeometryBox mTransformBox; // [reset] see nsStyleConsts.h
   RefPtr<nsCSSValueSharedList> mSpecifiedTransform; // [reset]
   nsStyleCoord mTransformOrigin[3]; // [reset] percent, coord, calc, 3rd param is coord, calc only
   nsStyleCoord mChildPerspective; // [reset] none, coord
   nsStyleCoord mPerspectiveOrigin[2]; // [reset] percent, coord, calc
 
   nsStyleCoord mVerticalAlign;  // [reset] coord, percent, calc, enum (see nsStyleConsts.h)
 
   nsStyleAutoArray<mozilla::StyleTransition> mTransitions; // [reset]

--- a/layout/style/nsStyleTransformMatrix.cpp
+++ b/layout/style/nsStyleTransformMatrix.cpp
@@ -53,38 +53,36 @@ TransformReferenceBox::EnsureDimensionsA
   if (mFrame->GetStateBits() & NS_FRAME_SVG_LAYOUT) {
     if (!nsLayoutUtils::SVGTransformBoxEnabled()) {
       mX = -mFrame->GetPosition().x;
       mY = -mFrame->GetPosition().y;
       Size contextSize = nsSVGUtils::GetContextSize(mFrame);
       mWidth = nsPresContext::CSSPixelsToAppUnits(contextSize.width);
       mHeight = nsPresContext::CSSPixelsToAppUnits(contextSize.height);
     } else
-    if (mFrame->StyleDisplay()->mTransformBox ==
-          NS_STYLE_TRANSFORM_BOX_FILL_BOX) {
+    if (mFrame->StyleDisplay()->mTransformBox == StyleGeometryBox::Fill) {
       // Percentages in transforms resolve against the SVG bbox, and the
       // transform is relative to the top-left of the SVG bbox.
-      gfxRect bbox = nsSVGUtils::GetBBox(const_cast<nsIFrame*>(mFrame));
       nsRect bboxInAppUnits =
-        nsLayoutUtils::RoundGfxRectToAppRect(bbox,
-                                             mFrame->PresContext()->AppUnitsPerCSSPixel());
+        nsLayoutUtils::ComputeGeometryBox(const_cast<nsIFrame*>(mFrame),
+                                          StyleGeometryBox::Fill);
       // The mRect of an SVG nsIFrame is its user space bounds *including*
       // stroke and markers, whereas bboxInAppUnits is its user space bounds
       // including fill only.  We need to note the offset of the reference box
       // from the frame's mRect in mX/mY.
       mX = bboxInAppUnits.x - mFrame->GetPosition().x;
       mY = bboxInAppUnits.y - mFrame->GetPosition().y;
       mWidth = bboxInAppUnits.width;
       mHeight = bboxInAppUnits.height;
     } else {
       // The value 'border-box' is treated as 'view-box' for SVG content.
       MOZ_ASSERT(mFrame->StyleDisplay()->mTransformBox ==
-                   NS_STYLE_TRANSFORM_BOX_VIEW_BOX ||
+                   StyleGeometryBox::View ||
                  mFrame->StyleDisplay()->mTransformBox ==
-                   NS_STYLE_TRANSFORM_BOX_BORDER_BOX,
+                   StyleGeometryBox::Border,
                  "Unexpected value for 'transform-box'");
       // Percentages in transforms resolve against the width/height of the
       // nearest viewport (or its viewBox if one is applied), and the
       // transform is relative to {0,0} in current user space.
       mX = -mFrame->GetPosition().x;
       mY = -mFrame->GetPosition().y;
       Size contextSize = nsSVGUtils::GetContextSize(mFrame);
       mWidth = nsPresContext::CSSPixelsToAppUnits(contextSize.width);