--- a/dom/base/DOMQuad.cpp
+++ b/dom/base/DOMQuad.cpp
@@ -10,17 +10,17 @@
 #include "mozilla/dom/DOMPoint.h"
 #include "mozilla/dom/DOMRect.h"
 #include <algorithm>
 
 using namespace mozilla;
 using namespace mozilla::dom;
 using namespace mozilla::gfx;
 
-NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(DOMQuad, mParent, mPoints[0],
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(DOMQuad, mParent, mBounds, mPoints[0],
                                       mPoints[1], mPoints[2], mPoints[3])
 
 NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(DOMQuad, AddRef)
 NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(DOMQuad, Release)
 
 DOMQuad::DOMQuad(nsISupports* aParent, CSSPoint aPoints[4])
   : mParent(aParent)
 {
@@ -97,21 +97,39 @@ DOMQuad::GetVerticalMinMax(double* aY1, 
     double y = Point(i)->Y();
     y1 = std::min(y1, y);
     y2 = std::max(y2, y);
   }
   *aY1 = y1;
   *aY2 = y2;
 }
 
+DOMRectReadOnly*
+DOMQuad::Bounds()
+{
+  if (!mBounds) {
+    mBounds = GetBounds();
+  }
+  return mBounds;
+}
+
 already_AddRefed<DOMRectReadOnly>
 DOMQuad::GetBounds() const
 {
   double x1, x2;
   double y1, y2;
 
   GetHorizontalMinMax(&x1, &x2);
   GetVerticalMinMax(&y1, &y2);
 
   RefPtr<DOMRectReadOnly> rval = new DOMRectReadOnly(GetParentObject(),
                                                      x1, y1, x2 - x1, y2 - y1);
   return rval.forget();
 }
+
+void
+DOMQuad::ToJSON(DOMQuadJSON& aInit)
+{
+  aInit.mP1.Construct(RefPtr<DOMPoint>(P1()).forget());
+  aInit.mP2.Construct(RefPtr<DOMPoint>(P2()).forget());
+  aInit.mP3.Construct(RefPtr<DOMPoint>(P3()).forget());
+  aInit.mP4.Construct(RefPtr<DOMPoint>(P4()).forget());
+}

--- a/dom/base/DOMQuad.h
+++ b/dom/base/DOMQuad.h
@@ -16,16 +16,17 @@
 #include "mozilla/ErrorResult.h"
 #include "Units.h"
 
 namespace mozilla {
 namespace dom {
 
 class DOMRectReadOnly;
 class DOMPoint;
+struct DOMQuadJSON;
 struct DOMPointInit;
 
 class DOMQuad final : public nsWrapperCache
 {
   ~DOMQuad();
 
 public:
   DOMQuad(nsISupports* aParent, CSSPoint aPoints[4]);
@@ -43,28 +44,32 @@ public:
               const DOMPointInit& aP2,
               const DOMPointInit& aP3,
               const DOMPointInit& aP4,
               ErrorResult& aRV);
   static already_AddRefed<DOMQuad>
   Constructor(const GlobalObject& aGlobal, const DOMRectReadOnly& aRect,
               ErrorResult& aRV);
 
+  DOMRectReadOnly* Bounds();
   already_AddRefed<DOMRectReadOnly> GetBounds() const;
   DOMPoint* P1() const { return mPoints[0]; }
   DOMPoint* P2() const { return mPoints[1]; }
   DOMPoint* P3() const { return mPoints[2]; }
   DOMPoint* P4() const { return mPoints[3]; }
 
   DOMPoint* Point(uint32_t aIndex) const { return mPoints[aIndex]; }
 
+  void ToJSON(DOMQuadJSON& aInit);
+
 protected:
   void GetHorizontalMinMax(double* aX1, double* aX2) const;
   void GetVerticalMinMax(double* aY1, double* aY2) const;
 
   nsCOMPtr<nsISupports> mParent;
   RefPtr<DOMPoint> mPoints[4];
+  RefPtr<DOMRectReadOnly> mBounds;
 };
 
 } // namespace dom
 } // namespace mozilla
 
 #endif /*MOZILLA_DOMRECT_H_*/

--- a/dom/base/nsDeprecatedOperationList.h
+++ b/dom/base/nsDeprecatedOperationList.h
@@ -43,8 +43,9 @@ DEPRECATED_OPERATION(RegisterProtocolHan
 DEPRECATED_OPERATION(MixedDisplayObjectSubrequest)
 DEPRECATED_OPERATION(MotionEvent)
 DEPRECATED_OPERATION(OrientationEvent)
 DEPRECATED_OPERATION(ProximityEvent)
 DEPRECATED_OPERATION(AmbientLightEvent)
 DEPRECATED_OPERATION(IDBOpenDBOptions_StorageType)
 DEPRECATED_OPERATION(DOMAttrModifiedEvent)
 DEPRECATED_OPERATION(MozBoxOrInlineBoxDisplay)
+DEPRECATED_OPERATION(DOMQuadBoundsAttr)

--- a/dom/locales/en-US/chrome/dom/dom.properties
+++ b/dom/locales/en-US/chrome/dom/dom.properties
@@ -353,8 +353,9 @@ ReadableStreamReadingFailed=Failed to read data from the ReadableStream: “%S”.
 RegisterProtocolHandlerInsecureWarning=Use of the registerProtocolHandler for insecure connections will be removed in version 62.
 MixedDisplayObjectSubrequestWarning=Loading insecure content within a plugin embedded in a secure connection is going to be removed.
 MotionEventWarning=Use of the motion sensor is deprecated.
 OrientationEventWarning=Use of the orientation sensor is deprecated.
 ProximityEventWarning=Use of the proximity sensor is deprecated.
 AmbientLightEventWarning=Use of the ambient light sensor is deprecated.
 # LOCALIZATION NOTE: Do not translate "storage", "indexedDB.open" and "navigator.storage.persist()".
 IDBOpenDBOptions_StorageTypeWarning=The ‘storage’ attribute in options passed to indexedDB.open is deprecated and will soon be removed. To get persistent storage, please use navigator.storage.persist() instead.
+DOMQuadBoundsAttrWarning=DOMQuad.bounds is deprecated in favor of DOMQuad.getBounds()

--- a/dom/webidl/DOMQuad.webidl
+++ b/dom/webidl/DOMQuad.webidl
@@ -16,10 +16,26 @@
  Constructor(DOMRectReadOnly rect)]
 interface DOMQuad {
     [SameObject] readonly attribute DOMPoint p1;
     [SameObject] readonly attribute DOMPoint p2;
     [SameObject] readonly attribute DOMPoint p3;
     [SameObject] readonly attribute DOMPoint p4;
     [NewObject] DOMRectReadOnly getBounds();
 
-    [Default] object toJSON();
+    [SameObject, Deprecated=DOMQuadBoundsAttr] readonly attribute DOMRectReadOnly bounds;
+
+    DOMQuadJSON toJSON();
 };
+
+dictionary DOMQuadJSON {
+    DOMPoint p1;
+    DOMPoint p2;
+    DOMPoint p3;
+    DOMPoint p4;
+};
+
+dictionary DOMQuadInit {
+    DOMPointInit p1;
+    DOMPointInit p2;
+    DOMPointInit p3;
+    DOMPointInit p4;
+};

--- a/testing/web-platform/meta/css/geometry/historical.html.ini
+++ b/testing/web-platform/meta/css/geometry/historical.html.ini
@@ -1,15 +1,18 @@
 [historical.html]
   [DOMMatrixReadOnly scaleNonUniform must be nuked]
     expected: FAIL
 
   [DOMMatrix scaleNonUniformSelf must be nuked]
     expected: FAIL
 
+  [DOMQuad bounds must be nuked]
+    expected: FAIL
+
   [DOMMatrixReadOnly scale number of required arguments]
     expected: FAIL
 
   [DOMMatrix scaleSelf number of required arguments]
     expected: FAIL
 
   [DOMMatrixReadOnly translate number of required arguments]
     expected: FAIL