--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -1489,18 +1489,17 @@ CSS_PROP_SHORTHAND(
     Columns,
     CSS_PROPERTY_PARSE_FUNCTION,
     "")
 CSS_PROP_DISPLAY(
     contain,
     contain,
     Contain,
     CSS_PROPERTY_PARSE_VALUE |
-        CSS_PROPERTY_VALUE_PARSER_FUNCTION |
-        CSS_PROPERTY_FIXPOS_CB,
+        CSS_PROPERTY_VALUE_PARSER_FUNCTION,
     "layout.css.contain.enabled",
     // Does not affect parsing, but is needed for tab completion in devtools:
     VARIANT_HK | VARIANT_NONE,
     kContainKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Discrete)
 CSS_PROP_CONTENT(
     content,
@@ -1648,18 +1647,17 @@ CSS_PROP_SVG(
     kFillRuleKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Discrete)
 CSS_PROP_EFFECTS(
     filter,
     filter,
     Filter,
     CSS_PROPERTY_PARSE_FUNCTION |
-        CSS_PROPERTY_CREATES_STACKING_CONTEXT |
-        CSS_PROPERTY_FIXPOS_CB,
+        CSS_PROPERTY_CREATES_STACKING_CONTEXT,
     "",
     0,
     nullptr,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Custom)
 CSS_PROP_SHORTHAND(
     flex,
     flex,
@@ -3362,18 +3360,17 @@ CSS_PROP_SVG(
     nullptr,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Discrete)
 CSS_PROP_DISPLAY(
     perspective,
     perspective,
     Perspective,
     CSS_PROPERTY_PARSE_VALUE |
-        CSS_PROPERTY_CREATES_STACKING_CONTEXT |
-        CSS_PROPERTY_FIXPOS_CB,
+        CSS_PROPERTY_CREATES_STACKING_CONTEXT,
     "",
     VARIANT_NONE | VARIANT_INHERIT | VARIANT_LENGTH |
       VARIANT_NONNEGATIVE_DIMENSION,
     nullptr,
     offsetof(nsStyleDisplay, mChildPerspective),
     eStyleAnimType_Coord)
 CSS_PROP_DISPLAY(
     perspective-origin,
@@ -3417,18 +3414,17 @@ CSS_PROP_USERINTERFACE(
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Discrete)
 CSS_PROP_DISPLAY(
     position,
     position,
     Position,
     CSS_PROPERTY_PARSE_VALUE |
         // For position: sticky/fixed
-        CSS_PROPERTY_CREATES_STACKING_CONTEXT |
-        CSS_PROPERTY_ABSPOS_CB,
+        CSS_PROPERTY_CREATES_STACKING_CONTEXT,
     "",
     VARIANT_HK,
     kPositionKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Discrete)
 CSS_PROP_LIST(
     quotes,
     quotes,
@@ -3467,18 +3463,17 @@ CSS_PROP_POSITION(
     offsetof(nsStylePosition, mOffset),
     eStyleAnimType_Sides_Right)
 CSS_PROP_DISPLAY(
     rotate,
     rotate,
     Rotate,
     CSS_PROPERTY_PARSE_FUNCTION |
         CSS_PROPERTY_GETCS_NEEDS_LAYOUT_FLUSH |
-        CSS_PROPERTY_CREATES_STACKING_CONTEXT |
-        CSS_PROPERTY_FIXPOS_CB,
+        CSS_PROPERTY_CREATES_STACKING_CONTEXT,
     "layout.css.individual-transform.enabled",
     0,
     nullptr,
     offsetof(nsStyleDisplay, mSpecifiedRotate),
     eStyleAnimType_None)
 CSS_PROP_TEXT(
     ruby-align,
     ruby_align,
@@ -4106,18 +4101,17 @@ CSS_PROP_TEXT(
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Discrete)
 CSS_PROP_DISPLAY(
     scale,
     scale,
     Scale,
     CSS_PROPERTY_PARSE_FUNCTION |
         CSS_PROPERTY_GETCS_NEEDS_LAYOUT_FLUSH |
-        CSS_PROPERTY_CREATES_STACKING_CONTEXT |
-        CSS_PROPERTY_FIXPOS_CB,
+        CSS_PROPERTY_CREATES_STACKING_CONTEXT,
     "layout.css.individual-transform.enabled",
     0,
     nullptr,
     offsetof(nsStyleDisplay, mSpecifiedScale),
     eStyleAnimType_None)
 CSS_PROP_TEXT(
     text-transform,
     text_transform,
@@ -4185,18 +4179,17 @@ CSS_PROP_DISPLAY(
     eStyleAnimType_Discrete)
 CSS_PROP_DISPLAY(
     transform,
     transform,
     Transform,
     CSS_PROPERTY_PARSE_FUNCTION |
         CSS_PROPERTY_GETCS_NEEDS_LAYOUT_FLUSH |
         CSS_PROPERTY_CREATES_STACKING_CONTEXT |
-        CSS_PROPERTY_CAN_ANIMATE_ON_COMPOSITOR |
-        CSS_PROPERTY_FIXPOS_CB,
+        CSS_PROPERTY_CAN_ANIMATE_ON_COMPOSITOR,
     "",
     0,
     nullptr,
     offsetof(nsStyleDisplay, mSpecifiedTransform),
     eStyleAnimType_Custom)
 CSS_PROP_DISPLAY(
     transform-box,
     transform_box,
@@ -4219,18 +4212,17 @@ CSS_PROP_DISPLAY(
     kImageLayerPositionKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Custom)
 CSS_PROP_DISPLAY(
     transform-style,
     transform_style,
     TransformStyle,
     CSS_PROPERTY_PARSE_VALUE |
-        CSS_PROPERTY_CREATES_STACKING_CONTEXT |
-        CSS_PROPERTY_FIXPOS_CB,
+        CSS_PROPERTY_CREATES_STACKING_CONTEXT,
     "",
     VARIANT_HK,
     kTransformStyleKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Discrete)
 CSS_PROP_SHORTHAND(
     transition,
     transition,
@@ -4282,18 +4274,17 @@ CSS_PROP_DISPLAY(
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_None)
 CSS_PROP_DISPLAY(
     translate,
     translate,
     Translate,
     CSS_PROPERTY_PARSE_FUNCTION |
         CSS_PROPERTY_GETCS_NEEDS_LAYOUT_FLUSH |
-        CSS_PROPERTY_CREATES_STACKING_CONTEXT |
-        CSS_PROPERTY_FIXPOS_CB,
+        CSS_PROPERTY_CREATES_STACKING_CONTEXT,
     "layout.css.individual-transform.enabled",
     0,
     nullptr,
     offsetof(nsStyleDisplay, mSpecifiedTranslate),
     eStyleAnimType_None)
 #ifndef CSS_PROP_LIST_ONLY_COMPONENTS_OF_ALL_SHORTHAND
 CSS_PROP_TEXTRESET(
     unicode-bidi,

--- a/layout/style/nsCSSProps.h
+++ b/layout/style/nsCSSProps.h
@@ -254,32 +254,16 @@ static_assert((CSS_PROPERTY_PARSE_PROPER
 // This property can be animated on the compositor.
 #define CSS_PROPERTY_CAN_ANIMATE_ON_COMPOSITOR    (1<<27)
 
 // This property is an internal property that is not represented
 // in the DOM.  Properties with this flag must be defined in an #ifndef
 // CSS_PROP_LIST_EXCLUDE_INTERNAL section of nsCSSPropList.h.
 #define CSS_PROPERTY_INTERNAL                     (1<<28)
 
-// This property has values that can establish a containing block for
-// fixed positioned and absolutely positioned elements.
-// This should be set for any properties that can cause an element to be
-// such a containing block, as implemented in
-// nsStyleDisplay::IsFixedPosContainingBlock.
-#define CSS_PROPERTY_FIXPOS_CB                    (1<<29)
-
-// This property has values that can establish a containing block for
-// absolutely positioned elements.
-// This should be set for any properties that can cause an element to be
-// such a containing block, as implemented in
-// nsStyleDisplay::IsAbsPosContainingBlock.
-// It does not need to be set for properties that also have
-// CSS_PROPERTY_FIXPOS_CB set.
-#define CSS_PROPERTY_ABSPOS_CB                    (1<<30)
-
 // This property should add Cross Origin Request headers to any loads
 // that it triggers. Currently this is only used for properties that
 // also use CSS_PROPERTY_START_IMAGE_LOADS.
 #define CSS_PROPERTY_LOAD_USE_CORS                (1U<<31)
 
 /**
  * Types of animatable values.
  */

--- a/layout/style/nsStyleStructInlines.h
+++ b/layout/style/nsStyleStructInlines.h
@@ -148,17 +148,17 @@ nsStyleDisplay::HasTransform(const nsIFr
 }
 
 template<class ComputedStyleLike>
 bool
 nsStyleDisplay::HasFixedPosContainingBlockStyleInternal(
                   ComputedStyleLike* aComputedStyle) const
 {
   // NOTE: Any CSS properties that influence the output of this function
-  // should have the CSS_PROPERTY_FIXPOS_CB set on them.
+  // should have the FIXPOS_CB flag set on them.
   NS_ASSERTION(aComputedStyle->ThreadsafeStyleDisplay() == this,
                "unexpected aComputedStyle");
 
   if (IsContainPaint() || HasPerspectiveStyle()) {
     return true;
   }
 
   if (mWillChangeBitField & NS_STYLE_WILL_CHANGE_FIXPOS_CB) {
@@ -169,62 +169,62 @@ nsStyleDisplay::HasFixedPosContainingBlo
 }
 
 template<class ComputedStyleLike>
 bool
 nsStyleDisplay::IsFixedPosContainingBlockForAppropriateFrame(
                   ComputedStyleLike* aComputedStyle) const
 {
   // NOTE: Any CSS properties that influence the output of this function
-  // should have the CSS_PROPERTY_FIXPOS_CB set on them.
+  // should have the FIXPOS_CB flag set on them.
   return HasFixedPosContainingBlockStyleInternal(aComputedStyle) ||
          HasTransformStyle();
 }
 
 bool
 nsStyleDisplay::IsFixedPosContainingBlock(const nsIFrame* aContextFrame) const
 {
   // NOTE: Any CSS properties that influence the output of this function
-  // should have the CSS_PROPERTY_FIXPOS_CB set on them.
+  // should have the FIXPOS_CB flag set on them.
   if (!HasFixedPosContainingBlockStyleInternal(aContextFrame->Style()) &&
       !HasTransform(aContextFrame)) {
     return false;
   }
   return !nsSVGUtils::IsInSVGTextSubtree(aContextFrame);
 }
 
 template<class ComputedStyleLike>
 bool
 nsStyleDisplay::HasAbsPosContainingBlockStyleInternal(
                   ComputedStyleLike* aComputedStyle) const
 {
   // NOTE: Any CSS properties that influence the output of this function
-  // should have the CSS_PROPERTY_ABSPOS_CB set on them.
+  // should have the ABSPOS_CB set on them.
   NS_ASSERTION(aComputedStyle->ThreadsafeStyleDisplay() == this,
                "unexpected aComputedStyle");
   return IsAbsolutelyPositionedStyle() ||
          IsRelativelyPositionedStyle() ||
          (mWillChangeBitField & NS_STYLE_WILL_CHANGE_ABSPOS_CB);
 }
 
 template<class ComputedStyleLike>
 bool
 nsStyleDisplay::IsAbsPosContainingBlockForAppropriateFrame(ComputedStyleLike* aComputedStyle) const
 {
   // NOTE: Any CSS properties that influence the output of this function
-  // should have the CSS_PROPERTY_ABSPOS_CB set on them.
+  // should have the ABSPOS_CB set on them.
   return HasAbsPosContainingBlockStyleInternal(aComputedStyle) ||
          IsFixedPosContainingBlockForAppropriateFrame(aComputedStyle);
 }
 
 bool
 nsStyleDisplay::IsAbsPosContainingBlock(const nsIFrame* aContextFrame) const
 {
   // NOTE: Any CSS properties that influence the output of this function
-  // should have the CSS_PROPERTY_ABSPOS_CB set on them.
+  // should have the ABSPOS_CB set on them.
   mozilla::ComputedStyle* sc = aContextFrame->Style();
   if (!HasAbsPosContainingBlockStyleInternal(sc) &&
       !HasFixedPosContainingBlockStyleInternal(sc) &&
       !HasTransform(aContextFrame)) {
     return false;
   }
   return !nsSVGUtils::IsInSVGTextSubtree(aContextFrame);
 }