--- a/dom/base/nsWindowMemoryReporter.cpp
+++ b/dom/base/nsWindowMemoryReporter.cpp
@@ -486,20 +486,18 @@ CollectWindowReports(nsGlobalWindowInner
       styleSundriesSize += size; \
     } else { \
       REPORT_SUM_SIZE( \
         "/layout/style-structs/" # name_, size, \
         "Memory used by the " #name_ " style structs within a window."); \
     } \
     aWindowTotalSizes->mStyleSizes.NS_STYLE_SIZES_FIELD(name_) += size; \
   }
-#define STYLE_STRUCT_LIST_IGNORE_VARIABLES
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
-#undef STYLE_STRUCT_LIST_IGNORE_VARIABLES
 
   if (styleSundriesSize > 0) {
     REPORT_SUM_SIZE(
       "/layout/style-structs/sundries", styleSundriesSize,
       "The sum of all memory used by style structs which were too "
       "small to be shown individually.");
   }
 
@@ -685,20 +683,18 @@ nsWindowMemoryReporter::CollectReports(n
   REPORT("window-objects/layout/frames", frameTotal,
          "Memory used for layout frames within windows. "
          "This is the sum of all windows' 'layout/frames/' numbers.");
 
   size_t styleTotal = 0;
 #define STYLE_STRUCT(name_) \
   styleTotal += \
     windowTotalSizes.mStyleSizes.NS_STYLE_SIZES_FIELD(name_);
-#define STYLE_STRUCT_LIST_IGNORE_VARIABLES
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
-#undef STYLE_STRUCT_LIST_IGNORE_VARIABLES
 
   REPORT("window-objects/layout/style-structs", styleTotal,
          "Memory used for style structs within windows. This is the sum of "
          "all windows' 'layout/style-structs/' numbers.");
 
 #undef REPORT
 
   return NS_OK;

--- a/dom/base/nsWindowSizes.h
+++ b/dom/base/nsWindowSizes.h
@@ -49,54 +49,46 @@ public:
 #define NS_STYLE_SIZES_FIELD(name_) mStyle##name_
 
 struct nsStyleSizes
 {
   nsStyleSizes()
     :
       #define STYLE_STRUCT(name_) \
         NS_STYLE_SIZES_FIELD(name_)(0),
-      #define STYLE_STRUCT_LIST_IGNORE_VARIABLES
       #include "nsStyleStructList.h"
       #undef STYLE_STRUCT
-      #undef STYLE_STRUCT_LIST_IGNORE_VARIABLES
 
       dummy()
   {}
 
   void addToTabSizes(nsTabSizes* aSizes) const
   {
     #define STYLE_STRUCT(name_) \
       aSizes->add(nsTabSizes::Style, NS_STYLE_SIZES_FIELD(name_));
-    #define STYLE_STRUCT_LIST_IGNORE_VARIABLES
     #include "nsStyleStructList.h"
     #undef STYLE_STRUCT
-    #undef STYLE_STRUCT_LIST_IGNORE_VARIABLES
   }
 
   size_t getTotalSize() const
   {
     size_t total = 0;
 
     #define STYLE_STRUCT(name_) \
       total += NS_STYLE_SIZES_FIELD(name_);
-    #define STYLE_STRUCT_LIST_IGNORE_VARIABLES
     #include "nsStyleStructList.h"
     #undef STYLE_STRUCT
-    #undef STYLE_STRUCT_LIST_IGNORE_VARIABLES
 
     return total;
   }
 
   #define STYLE_STRUCT(name_) \
     size_t NS_STYLE_SIZES_FIELD(name_);
-  #define STYLE_STRUCT_LIST_IGNORE_VARIABLES
   #include "nsStyleStructList.h"
   #undef STYLE_STRUCT
-  #undef STYLE_STRUCT_LIST_IGNORE_VARIABLES
 
   // Present just to absorb the trailing comma in the constructor.
   int dummy;
 };
 
 #define NS_ARENA_SIZES_FIELD(classname) mArena##classname
 
 struct nsArenaSizes {

--- a/layout/style/ComputedStyle.cpp
+++ b/layout/style/ComputedStyle.cpp
@@ -108,18 +108,17 @@ ComputedStyle::CalcStyleDifference(Compu
   // style change, the PeekStyleData doesn't return null (implying that
   // nobody ever looked at that struct's data).  In other words, we
   // can't skip later structs if we get a big change up front, because
   // we could later get a small change in one of those structs that we
   // don't want to miss.
 
   DebugOnly<uint32_t> structsFound = 0;
 
-  *aEqualStructs |= NS_STYLE_INHERIT_BIT(Variables);
-  DebugOnly<int> styleStructCount = 1;  // count Variables already
+  DebugOnly<int> styleStructCount = 0;
 
   // Servo's optimization to stop the cascade when there are no style changes
   // that children need to be recascade for relies on comparing all of the
   // structs, not just those that are returned from PeekStyleData, although
   // if PeekStyleData does return null we could avoid to accumulate any change
   // hints for those structs.
   //
   // FIXME(emilio): Reintroduce that optimization either for all kind of structs
@@ -187,25 +186,23 @@ ComputedStyle::CalcStyleDifference(Compu
 #undef DO_STRUCT_DIFFERENCE
 #undef DO_STRUCT_DIFFERENCE_WITH_ARGS
 #undef EXPAND
 
   MOZ_ASSERT(styleStructCount == nsStyleStructID_Length,
              "missing a call to DO_STRUCT_DIFFERENCE");
 
 #ifdef DEBUG
-  #define STYLE_STRUCT_LIST_IGNORE_VARIABLES
   #define STYLE_STRUCT(name_)                                             \
     MOZ_ASSERT(!!(structsFound & NS_STYLE_INHERIT_BIT(name_)) ==          \
                (PEEK(name_) != nullptr),                                  \
                "PeekStyleData results must not change in the middle of "  \
                "difference calculation.");
   #include "nsStyleStructList.h"
   #undef STYLE_STRUCT
-  #undef STYLE_STRUCT_LIST_IGNORE_VARIABLES
 #endif
 
   // Note that we do not check whether this->RelevantLinkVisited() !=
   // aNewContext->RelevantLinkVisited(); we don't need to since
   // nsCSSFrameConstructor::DoContentStateChanged always adds
   // nsChangeHint_RepaintFrame for NS_EVENT_STATE_VISITED changes (and
   // needs to, since HasStateDependentStyle probably doesn't work right
   // for NS_EVENT_STATE_VISITED).  Hopefully this doesn't actually

--- a/layout/style/ComputedStyle.h
+++ b/layout/style/ComputedStyle.h
@@ -20,27 +20,28 @@
 #include "nsCSSAnonBoxes.h"
 #include "nsCSSPseudoElements.h"
 
 // Includes nsStyleStructID.
 #include "nsStyleStructFwd.h"
 
 // Bits for each struct.
 // NS_STYLE_INHERIT_BIT defined in nsStyleStructFwd.h
-#define NS_STYLE_INHERIT_MASK              0x000ffffff
+#define NS_STYLE_INHERIT_MASK              0x0007fffff
 
 // Bits for inherited structs.
 #define NS_STYLE_INHERITED_STRUCT_MASK \
   ((nsStyleStructID_size_t(1) << nsStyleStructID_Inherited_Count) - 1)
 // Bits for reset structs.
 #define NS_STYLE_RESET_STRUCT_MASK \
   (((nsStyleStructID_size_t(1) << nsStyleStructID_Reset_Count) - 1) \
    << nsStyleStructID_Inherited_Count)
 
 // Additional bits for ComputedStyle's mBits:
+// (free bit)                              0x000800000
 // See ComputedStyle::HasTextDecorationLines
 #define NS_STYLE_HAS_TEXT_DECORATION_LINES 0x001000000
 // See ComputedStyle::HasPseudoElementData.
 #define NS_STYLE_HAS_PSEUDO_ELEMENT_DATA   0x002000000
 // See ComputedStyle::RelevantLinkIsVisited
 #define NS_STYLE_RELEVANT_LINK_VISITED     0x004000000
 // See ComputedStyle::IsStyleIfVisited
 #define NS_STYLE_IS_STYLE_IF_VISITED       0x008000000
@@ -346,18 +347,17 @@ public:
    * hints apply to the frame and its later continuations or ib-split
    * siblings.  Most (all of those except the "NotHandledForDescendants"
    * hints) also apply to all descendants.
    *
    * aEqualStructs must not be null.  Into it will be stored a bitfield
    * representing which structs were compared to be non-equal.
    *
    * CSS Variables are not compared here. Instead, the caller is responsible for
-   * that when needed (basically only for elements). The Variables bit in
-   * aEqualStructs is always set.
+   * that when needed (basically only for elements).
    */
   nsChangeHint CalcStyleDifference(ComputedStyle* aNewContext,
                                    uint32_t* aEqualStructs);
 
 public:
   /**
    * Get a color that depends on link-visitedness using this and
    * this->GetStyleIfVisited().
@@ -429,19 +429,18 @@ protected:
   #undef STYLE_STRUCT_RESET
   #undef STYLE_STRUCT_INHERITED
 
   // If this ComputedStyle is for a pseudo-element or anonymous box,
   // the relevant atom.
   RefPtr<nsAtom> mPseudoTag;
 
   // mBits stores a number of things:
-  //  - It records (using the style struct bits) which structs are
-  //    inherited from the parent context or owned by the rule node (i.e.,
-  //    not owned by the ComputedStyle).
+  //  - It records (using the style struct bits) which structs have
+  //    been requested on this ComputedStyle.
   //  - It also stores the additional bits listed at the top of
   //    nsStyleStruct.h.
   uint64_t                mBits;
 };
 
 } // namespace mozilla
 
 #endif

--- a/layout/style/ServoBindings.cpp
+++ b/layout/style/ServoBindings.cpp
@@ -198,23 +198,16 @@ Gecko_ComputedStyle_Init(
 }
 
 ServoComputedData::ServoComputedData(
     const ServoComputedDataForgotten aValue)
 {
   PodAssign(this, aValue.mPtr);
 }
 
-const nsStyleVariables*
-ServoComputedData::GetStyleVariables() const
-{
-  MOZ_CRASH("ServoComputedData::GetStyleVariables should never need to be "
-            "called");
-}
-
 MOZ_DEFINE_MALLOC_ENCLOSING_SIZE_OF(ServoStyleStructsMallocEnclosingSizeOf)
 
 void
 ServoComputedData::AddSizeOfExcludingThis(nsWindowSizes& aSizes) const
 {
   // Note: GetStyleFoo() returns a pointer to an nsStyleFoo that sits within a
   // servo_arc::Arc, i.e. it is preceded by a word-sized refcount. So we need
   // to measure it with a function that can handle an interior pointer. We use
@@ -223,20 +216,18 @@ ServoComputedData::AddSizeOfExcludingThi
 #define STYLE_STRUCT(name_) \
   static_assert(alignof(nsStyle##name_) <= sizeof(size_t), \
                 "alignment will break AddSizeOfExcludingThis()"); \
   const void* p##name_ = GetStyle##name_(); \
   if (!aSizes.mState.HaveSeenPtr(p##name_)) { \
     aSizes.mStyleSizes.NS_STYLE_SIZES_FIELD(name_) += \
       ServoStyleStructsMallocEnclosingSizeOf(p##name_); \
   }
-  #define STYLE_STRUCT_LIST_IGNORE_VARIABLES
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
-#undef STYLE_STRUCT_LIST_IGNORE_VARIABLES
 
   if (visited_style.mPtr && !aSizes.mState.HaveSeenPtr(visited_style.mPtr)) {
     visited_style.mPtr->AddSizeOfIncludingThis(
       aSizes, &aSizes.mLayoutComputedValuesVisited);
   }
 
   // Measurement of the following members may be added later if DMD finds it is
   // worthwhile:

--- a/layout/style/ServoBindings.h
+++ b/layout/style/ServoBindings.h
@@ -81,20 +81,18 @@ const bool GECKO_IS_NIGHTLY = false;
 namespace mozilla {
   #define STYLE_STRUCT(name_) struct Gecko##name_ {nsStyle##name_ gecko;};
   #include "nsStyleStructList.h"
   #undef STYLE_STRUCT
 }
 
 #define STYLE_STRUCT(name_) \
   const nsStyle##name_* ServoComputedData::GetStyle##name_() const { return &name_.mPtr->gecko; }
-#define STYLE_STRUCT_LIST_IGNORE_VARIABLES
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
-#undef STYLE_STRUCT_LIST_IGNORE_VARIABLES
 
 #define NS_DECL_THREADSAFE_FFI_REFCOUNTING(class_, name_)                     \
   void Gecko_AddRef##name_##ArbitraryThread(class_* aPtr);                    \
   void Gecko_Release##name_##ArbitraryThread(class_* aPtr);
 #define NS_IMPL_THREADSAFE_FFI_REFCOUNTING(class_, name_)                     \
   static_assert(class_::HasThreadSafeRefCnt::value,                           \
                 "NS_DECL_THREADSAFE_FFI_REFCOUNTING can only be used with "   \
                 "classes that have thread-safe refcounting");                 \

--- a/layout/style/ServoBindings.toml
+++ b/layout/style/ServoBindings.toml
@@ -336,17 +336,16 @@ whitelist-types = [
     "nsStyleTable",
     "nsStyleTableBorder",
     "nsStyleText",
     "nsStyleTextReset",
     "nsStyleUIReset",
     "nsStyleUnion",
     "nsStyleUnit",
     "nsStyleUserInterface",
-    "nsStyleVariables",
     "nsStyleVisibility",
     "nsStyleXUL",
     "nsTArrayHeader",
     "Position",
     "PropertyValuePair",
     "Runnable",
     "ServoAttrSnapshot",
     "ServoBundledURI",
@@ -578,17 +577,16 @@ structs-types = [
     "nsStyleTable",
     "nsStyleTableBorder",
     "nsStyleText",
     "nsStyleTextReset",
     "nsStyleUIReset",
     "nsStyleUnion",
     "nsStyleUnit",
     "nsStyleUserInterface",
-    "nsStyleVariables",
     "nsStyleVisibility",
     "nsStyleXUL",
     "nsTimingFunction",
     "nscolor",
     "nscoord",
     "nsresult",
     "Loader",
     "LoaderReusableStyleSheets",

--- a/layout/style/ServoTypes.h
+++ b/layout/style/ServoTypes.h
@@ -159,20 +159,18 @@ struct ServoRawOffsetArc {
   T* mPtr;
 };
 
 struct ServoComputedValueFlags {
   uint16_t mFlags;
 };
 
 #define STYLE_STRUCT(name_) struct Gecko##name_;
-#define STYLE_STRUCT_LIST_IGNORE_VARIABLES
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
-#undef STYLE_STRUCT_LIST_IGNORE_VARIABLES
 
 // These measurements are obtained for both the UA cache and the Stylist, but
 // not all the fields are used in both cases.
 class ServoStyleSetSizes
 {
 public:
   size_t mRuleTree;                // Stylist-only
   size_t mPrecomputedPseudos;      // UA cache-only
@@ -214,21 +212,18 @@ class ServoComputedData
 
 public:
   // Constructs via memcpy.  Will not move out of aValue.
   explicit ServoComputedData(const ServoComputedDataForgotten aValue);
 
 #define STYLE_STRUCT(name_)                                \
   mozilla::ServoRawOffsetArc<mozilla::Gecko##name_> name_; \
   inline const nsStyle##name_* GetStyle##name_() const;
-  #define STYLE_STRUCT_LIST_IGNORE_VARIABLES
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
-#undef STYLE_STRUCT_LIST_IGNORE_VARIABLES
-  const nsStyleVariables* GetStyleVariables() const;
 
   void AddSizeOfExcludingThis(nsWindowSizes& aSizes) const;
 
 private:
   mozilla::ServoCustomPropertiesMap custom_properties;
   mozilla::ServoWritingMode writing_mode;
   mozilla::ServoComputedValueFlags flags;
   /// The rule node representing the ordered list of rules matched for this

--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -4778,46 +4778,16 @@ nsStyleUIReset::CalcDifference(const nsS
       mIMEMode != aNewData.mIMEMode) {
     hint |= nsChangeHint_NeutralChange;
   }
 
   return hint;
 }
 
 //-----------------------
-// nsStyleVariables
-//
-
-nsStyleVariables::nsStyleVariables()
-{
-  MOZ_COUNT_CTOR(nsStyleVariables);
-}
-
-nsStyleVariables::nsStyleVariables(const nsPresContext* aContext)
-{
-  MOZ_COUNT_CTOR(nsStyleVariables);
-}
-
-nsStyleVariables::nsStyleVariables(const nsStyleVariables& aSource)
-{
-  MOZ_COUNT_CTOR(nsStyleVariables);
-}
-
-nsStyleVariables::~nsStyleVariables()
-{
-  MOZ_COUNT_DTOR(nsStyleVariables);
-}
-
-nsChangeHint
-nsStyleVariables::CalcDifference(const nsStyleVariables& aNewData) const
-{
-  return nsChangeHint(0);
-}
-
-//-----------------------
 // nsStyleEffects
 //
 
 nsStyleEffects::nsStyleEffects(const nsPresContext* aContext)
   : mBoxShadow(nullptr)
   , mClip(0, 0, 0, 0)
   , mOpacity(1.0f)
   , mClipFlags(NS_STYLE_CLIP_AUTO)

--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -3249,30 +3249,16 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsSt
   float            mStopOpacity;      // [reset]
   float            mFloodOpacity;     // [reset]
 
   uint8_t          mDominantBaseline; // [reset] see nsStyleConsts.h
   uint8_t          mVectorEffect;     // [reset] see nsStyleConsts.h
   uint8_t          mMaskType;         // [reset] see nsStyleConsts.h
 };
 
-// XXX This can be removed once the old style system is gone.
-struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleVariables
-{
-  nsStyleVariables();
-  explicit nsStyleVariables(const nsPresContext* aContext);
-  nsStyleVariables(const nsStyleVariables& aSource);
-  ~nsStyleVariables();
-  void FinishStyle(nsPresContext*, const nsStyleVariables*) {}
-  const static bool kHasFinishStyle = false;
-
-  nsChangeHint CalcDifference(const nsStyleVariables& aNewData) const;
-
-};
-
 struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleEffects
 {
   explicit nsStyleEffects(const nsPresContext* aContext);
   nsStyleEffects(const nsStyleEffects& aSource);
   ~nsStyleEffects();
   void FinishStyle(nsPresContext*, const nsStyleEffects*) {}
   const static bool kHasFinishStyle = false;
 

--- a/layout/style/nsStyleStructList.h
+++ b/layout/style/nsStyleStructList.h
@@ -35,19 +35,16 @@
 STYLE_STRUCT_INHERITED(Font)
 STYLE_STRUCT_INHERITED(Color)
 STYLE_STRUCT_INHERITED(List)
 STYLE_STRUCT_INHERITED(Text)
 STYLE_STRUCT_INHERITED(Visibility)
 STYLE_STRUCT_INHERITED(UserInterface)
 STYLE_STRUCT_INHERITED(TableBorder)
 STYLE_STRUCT_INHERITED(SVG)
-#ifndef STYLE_STRUCT_LIST_IGNORE_VARIABLES
-STYLE_STRUCT_INHERITED(Variables)
-#endif
 
 STYLE_STRUCT_RESET(Background)
 STYLE_STRUCT_RESET(Position)
 STYLE_STRUCT_RESET(TextReset)
 STYLE_STRUCT_RESET(Display)
 STYLE_STRUCT_RESET(Content)
 STYLE_STRUCT_RESET(UIReset)
 STYLE_STRUCT_RESET(Table)