Make sure z-index is adjusted after applying pending animations on elements

third_party/WebKit/Source/core/dom/Element.cpp

Index: third_party/WebKit/Source/core/dom/Element.cpp
diff --git a/third_party/WebKit/Source/core/dom/Element.cpp b/third_party/WebKit/Source/core/dom/Element.cpp
index 6c7a4d1b5581b2799541bac69866ec108d4f9994..90d2caed7574571a546bcf1a1464764f657a3ff1 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -1659,6 +1659,13 @@ PassRefPtr<ComputedStyle> Element::styleForLayoutObject()
     if (ElementAnimations* elementAnimations = this->elementAnimations()) {
         elementAnimations->cssAnimations().maybeApplyPendingUpdate(this);
         elementAnimations->updateAnimationFlags(*style);
+
+        // This is supposed to be done by StyleAdjuster, but we may not have updated animation
+        // list until this point.
+        if (style->hasAutoZIndex() && (style->hasCurrentOpacityAnimation()
+            || style->hasCurrentTransformAnimation()
+            || style->hasCurrentFilterAnimation()))
+            style->setZIndex(0);
     }
 
     if (style->hasTransform()) {