--- a/dom/base/nsDeprecatedOperationList.h
+++ b/dom/base/nsDeprecatedOperationList.h
@@ -43,8 +43,9 @@ DEPRECATED_OPERATION(XMLBaseAttribute)
 DEPRECATED_OPERATION(WindowContentUntrusted)
 DEPRECATED_OPERATION(RegisterProtocolHandlerInsecure)
 DEPRECATED_OPERATION(MixedDisplayObjectSubrequest)
 DEPRECATED_OPERATION(MotionEvent)
 DEPRECATED_OPERATION(OrientationEvent)
 DEPRECATED_OPERATION(ProximityEvent)
 DEPRECATED_OPERATION(AmbientLightEvent)
 DEPRECATED_OPERATION(IDBOpenDBOptions_StorageType)
+DEPRECATED_OPERATION(GetPropertyCSSValue)

--- a/dom/locales/en-US/chrome/dom/dom.properties
+++ b/dom/locales/en-US/chrome/dom/dom.properties
@@ -356,8 +356,10 @@ 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.
+# LOCALIZATION NOTE: Do not translate "getPropertyCSSValue" and "getPropertyValue".
+GetPropertyCSSValueWarning=Use of getPropertyCSSValue is deprecated, use getPropertyValue instead.

--- a/layout/style/nsComputedDOMStyle.cpp
+++ b/layout/style/nsComputedDOMStyle.cpp
@@ -494,17 +494,18 @@ nsComputedDOMStyle::GetParentRule()
 
 NS_IMETHODIMP
 nsComputedDOMStyle::GetPropertyValue(const nsAString& aPropertyName,
                                      nsAString& aReturn)
 {
   aReturn.Truncate();
 
   ErrorResult error;
-  RefPtr<CSSValue> val = GetPropertyCSSValue(aPropertyName, error);
+  RefPtr<CSSValue> val =
+    GetPropertyCSSValueWithoutWarning(aPropertyName, error);
   if (error.Failed()) {
     return error.StealNSResult();
   }
 
   if (val) {
     nsString text;
     val->GetCssText(text, error);
     aReturn.Assign(text);
@@ -1286,17 +1287,29 @@ nsComputedDOMStyle::ClearCurrentStyleSou
   }
 
   mOuterFrame = nullptr;
   mInnerFrame = nullptr;
   mPresShell = nullptr;
 }
 
 already_AddRefed<CSSValue>
-nsComputedDOMStyle::GetPropertyCSSValue(const nsAString& aPropertyName, ErrorResult& aRv)
+nsComputedDOMStyle::GetPropertyCSSValue(const nsAString& aPropertyName,
+                                        ErrorResult& aRv)
+{
+  if (nsCOMPtr<nsIDocument> document = do_QueryReferent(mDocumentWeak)) {
+    document->WarnOnceAbout(nsIDocument::eGetPropertyCSSValue);
+  }
+  return GetPropertyCSSValueWithoutWarning(aPropertyName, aRv);
+}
+
+already_AddRefed<CSSValue>
+nsComputedDOMStyle::GetPropertyCSSValueWithoutWarning(
+  const nsAString& aPropertyName,
+  ErrorResult& aRv)
 {
   nsCSSPropertyID prop =
     nsCSSProps::LookupProperty(aPropertyName, CSSEnabledState::eForAllContent);
 
   bool needsLayoutFlush;
   nsComputedStyleMap::Entry::ComputeMethod getter;
 
   if (prop == eCSSPropertyExtra_variable) {

--- a/layout/style/nsComputedDOMStyle.h
+++ b/layout/style/nsComputedDOMStyle.h
@@ -53,32 +53,38 @@ class nsComputedDOMStyle final : public 
                                , public nsStubMutationObserver
 {
 private:
   // Convenience typedefs:
   typedef nsCSSProps::KTableEntry KTableEntry;
   typedef mozilla::dom::CSSValue CSSValue;
   typedef mozilla::StyleGeometryBox StyleGeometryBox;
 
+  already_AddRefed<CSSValue>
+  GetPropertyCSSValueWithoutWarning(const nsAString& aProp,
+                                    mozilla::ErrorResult& aRv);
+
 public:
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_SKIPPABLE_SCRIPT_HOLDER_CLASS_AMBIGUOUS(nsComputedDOMStyle,
                                                                    nsICSSDeclaration)
 
   NS_DECL_NSIDOMCSSSTYLEDECLARATION_HELPER
   nsresult GetPropertyValue(const nsCSSPropertyID aPropID,
                             nsAString& aValue) override;
   nsresult SetPropertyValue(const nsCSSPropertyID aPropID,
                             const nsAString& aValue,
                             nsIPrincipal* aSubjectPrincipal) override;
-  virtual already_AddRefed<CSSValue>
-  GetPropertyCSSValue(const nsAString& aProp, mozilla::ErrorResult& aRv)
-    override;
+
+  // Do NOT use this, it is deprecated, see bug 474655.
+  already_AddRefed<CSSValue>
+  GetPropertyCSSValue(const nsAString& aProp, mozilla::ErrorResult& aRv) final;
   using nsICSSDeclaration::GetPropertyCSSValue;
-  virtual void IndexedGetter(uint32_t aIndex, bool& aFound, nsAString& aPropName) override;
+
+  void IndexedGetter(uint32_t aIndex, bool& aFound, nsAString& aPropName) final;
 
   enum StyleType {
     eDefaultOnly, // Only includes UA and user sheets
     eAll // Includes all stylesheets
   };
 
   enum AnimationFlag {
     eWithAnimation,