--- a/layout/style/nsComputedDOMStyle.cpp
+++ b/layout/style/nsComputedDOMStyle.cpp
@@ -443,22 +443,62 @@ nsComputedDOMStyle::GetStyleContextForEl
   }
 
   presShell->FlushPendingNotifications(FlushType::Style);
 
   return GetStyleContextForElementNoFlush(aElement, aPseudo, presShell,
                                           aStyleType);
 }
 
-/* static */
+namespace {
+class MOZ_STACK_CLASS AutoSkipAnimationRules final
+{
+public:
+  AutoSkipAnimationRules(nsPresContext* aPresContext,
+                         nsComputedDOMStyle::AnimationFlag aAnimationFlag)
+  {
+    MOZ_ASSERT(aPresContext);
+
+    // Nothing to do if we are going to resolve style *with* animation.
+    if (aAnimationFlag == nsComputedDOMStyle::eWithAnimation) {
+      return;
+    }
+
+    // Set SkipAnimationRules flag if we are going to resolve style without
+    // animation.
+    if (aPresContext->RestyleManager()->IsGecko()) {
+      mRestyleManager = aPresContext->RestyleManager()->AsGecko();
+
+      mOldSkipAnimationRules = mRestyleManager->SkipAnimationRules();
+      mRestyleManager->SetSkipAnimationRules(true);
+    } else {
+      NS_WARNING("stylo: can't skip animaition rules yet");
+    }
+  }
+
+  ~AutoSkipAnimationRules()
+  {
+    if (mRestyleManager) {
+      mRestyleManager->SetSkipAnimationRules(mOldSkipAnimationRules);
+    }
+  }
+
+private:
+  RestyleManager* mRestyleManager = nullptr;
+  bool mOldSkipAnimationRules = false;
+};
+}
+
 already_AddRefed<nsStyleContext>
-nsComputedDOMStyle::GetStyleContextForElementNoFlush(Element* aElement,
-                                                     nsIAtom* aPseudo,
-                                                     nsIPresShell* aPresShell,
-                                                     StyleType aStyleType)
+nsComputedDOMStyle::DoGetStyleContextForElementNoFlush(
+  Element* aElement,
+  nsIAtom* aPseudo,
+  nsIPresShell* aPresShell,
+  StyleType aStyleType,
+  AnimationFlag aAnimationFlag)
 {
   MOZ_ASSERT(aElement, "NULL element");
   // If the content has a pres shell, we must use it.  Otherwise we'd
   // potentially mix rule trees by using the wrong pres shell's style
   // set.  Using the pres shell from the content also means that any
   // content that's actually *in* a document will get the style from the
   // correct document.
   nsIPresShell *presShell = GetPresShellForContent(aElement);
@@ -516,20 +556,23 @@ nsComputedDOMStyle::GetStyleContextForEl
     }
     return servoSet->ResolveTransientStyle(aElement, type);
   }
 
   RefPtr<nsStyleContext> sc;
   RefPtr<nsStyleContext> parentContext;
   nsIContent* parent = aPseudo ? aElement : aElement->GetParent();
   // Don't resolve parent context for document fragments.
-  if (parent && parent->IsElement())
+  if (parent && parent->IsElement()) {
     parentContext = GetStyleContextForElementNoFlush(parent->AsElement(),
                                                      nullptr, aPresShell,
                                                      aStyleType);
+  }
+
+  AutoSkipAnimationRules autoSkipAnimationRule(presContext, aAnimationFlag);
 
   if (type != CSSPseudoElementType::NotPseudo) {
     nsIFrame* frame = nsLayoutUtils::GetStyleFrame(aElement);
     Element* pseudoElement =
       frame && inDocWithShell ? frame->GetPseudoElement(type) : nullptr;
     sc = styleSet->ResolvePseudoElementStyle(aElement, type, parentContext,
                                              pseudoElement);
   } else {
@@ -558,16 +601,59 @@ nsComputedDOMStyle::GetStyleContextForEl
     }
 
     sc = styleSet->AsGecko()->ResolveStyleForRules(parentContext, rules);
   }
 
   return sc.forget();
 }
 
+
+/* static */
+already_AddRefed<nsStyleContext>
+nsComputedDOMStyle::GetStyleContextForElementNoFlush(Element* aElement,
+                                                     nsIAtom* aPseudo,
+                                                     nsIPresShell* aPresShell,
+                                                     StyleType aStyleType)
+{
+  return DoGetStyleContextForElementNoFlush(aElement,
+                                            aPseudo,
+                                            aPresShell,
+                                            aStyleType,
+                                            eWithAnimation);
+}
+
+/* static */
+already_AddRefed<nsStyleContext>
+nsComputedDOMStyle::GetStyleContextForElementWithoutAnimation(
+  Element* aElement,
+  nsIAtom* aPseudo,
+  nsIPresShell* aPresShell)
+{
+  // If the content has a pres shell, we must use it.  Otherwise we'd
+  // potentially mix rule trees by using the wrong pres shell's style
+  // set.  Using the pres shell from the content also means that any
+  // content that's actually *in* a document will get the style from the
+  // correct document.
+  nsCOMPtr<nsIPresShell> presShell = GetPresShellForContent(aElement);
+  if (!presShell) {
+    presShell = aPresShell;
+    if (!presShell)
+      return nullptr;
+  }
+
+  presShell->FlushPendingNotifications(FlushType::Style);
+
+  return DoGetStyleContextForElementNoFlush(aElement,
+                                            aPseudo,
+                                            presShell,
+                                            eAll,
+                                            eWithoutAnimation);
+}
+
 nsMargin
 nsComputedDOMStyle::GetAdjustedValuesForBoxSizing()
 {
   // We want the width/height of whatever parts 'width' or 'height' controls,
   // which can be different depending on the value of the 'box-sizing' property.
   const nsStylePosition* stylePos = StylePosition();
 
   nsMargin adjustment;

--- a/layout/style/nsComputedDOMStyle.h
+++ b/layout/style/nsComputedDOMStyle.h
@@ -84,16 +84,26 @@ public:
     return mContent;
   }
 
   static already_AddRefed<nsStyleContext>
   GetStyleContextForElement(mozilla::dom::Element* aElement, nsIAtom* aPseudo,
                             nsIPresShell* aPresShell,
                             StyleType aStyleType = eAll);
 
+  enum AnimationFlag {
+    eWithAnimation,
+    eWithoutAnimation,
+  };
+  // Similar to the above but ignoring animation rules and with StyleType::eAll.
+  static already_AddRefed<nsStyleContext>
+  GetStyleContextForElementWithoutAnimation(mozilla::dom::Element* aElement,
+                                            nsIAtom* aPseudo,
+                                            nsIPresShell* aPresShell);
+
   static already_AddRefed<nsStyleContext>
   GetStyleContextForElementNoFlush(mozilla::dom::Element* aElement,
                                    nsIAtom* aPseudo,
                                    nsIPresShell* aPresShell,
                                    StyleType aStyleType = eAll);
 
   static nsIPresShell*
   GetPresShellForContent(nsIContent* aContent);
@@ -139,16 +149,23 @@ private:
   void UpdateCurrentStyleSources(bool aNeedsLayoutFlush);
   void ClearCurrentStyleSources();
 
   // Helper functions called by UpdateCurrentStyleSources.
   void ClearStyleContext();
   void SetResolvedStyleContext(RefPtr<nsStyleContext>&& aContext);
   void SetFrameStyleContext(nsStyleContext* aContext);
 
+  static already_AddRefed<nsStyleContext>
+  DoGetStyleContextForElementNoFlush(mozilla::dom::Element* aElement,
+                                     nsIAtom* aPseudo,
+                                     nsIPresShell* aPresShell,
+                                     StyleType aStyleType,
+                                     AnimationFlag aAnimationFlag);
+
 #define STYLE_STRUCT(name_, checkdata_cb_)                              \
   const nsStyle##name_ * Style##name_() {                               \
     return mStyleContext->Style##name_();                               \
   }
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
 
   already_AddRefed<CSSValue> GetEllipseRadii(const nsStyleCorners& aRadius,