Use InDetach() to avoid marking style dirty animation cancelling.

This CL is a revert of [1] and an alternative fix for 1093747.

The original change caused increased memory use for some reason. It's
confirmed with a pinpoint job that this CL fixes that regression.

[1] https://crrev.com/c4a447a85cdb4de7740476a74c9d258feb0a976d

Bug: 1100637, 1093747
Change-Id: If13212db30f818e68649f56a5c68ca5221a73dc5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2278052Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#786202}

third_party/blink/renderer/core/animation/keyframe_effect.cc

@@ -527,7 +527,8 @@ void KeyframeEffect::ClearEffects() {
   sampled_effect_ = nullptr;
   if (GetAnimation())
     GetAnimation()->RestartAnimationOnCompositor();
-  effect_target_->SetNeedsAnimationStyleRecalc();
+  if (!effect_target_->GetDocument().Lifecycle().InDetach())
+    effect_target_->SetNeedsAnimationStyleRecalc();
   auto* svg_element = DynamicTo<SVGElement>(effect_target_.Get());
   if (RuntimeEnabledFeatures::WebAnimationsSVGEnabled() && svg_element)
     svg_element->ClearWebAnimatedAttributes();

third_party/blink/renderer/core/dom/element.cc

@@ -2874,6 +2874,24 @@ void Element::AttachLayoutTree(AttachContext& context) {
 
 void Element::DetachLayoutTree(bool performing_reattach) {
   HTMLFrameOwnerElement::PluginDisposeSuspendScope suspend_plugin_dispose;
+  if (HasRareData()) {
+    ElementRareData* data = GetElementRareData();
+    if (!performing_reattach)
+      data->ClearPseudoElements();
+
+    if (ElementAnimations* element_animations = data->GetElementAnimations()) {
+      if (performing_reattach) {
+        // FIXME: restart compositor animations rather than pull back to the
+        // main thread
+        element_animations->RestartAnimationOnCompositor();
+      } else {
+        DocumentLifecycle::DetachScope will_detach(GetDocument().Lifecycle());
+        element_animations->CssAnimations().Cancel();
+        element_animations->SetAnimationStyleChange(false);
+      }
+      element_animations->ClearBaseComputedStyle();
+    }
+  }
 
   DetachPseudoElement(kPseudoIdMarker, performing_reattach);
   DetachPseudoElement(kPseudoIdBefore, performing_reattach);
@@ -2888,10 +2906,6 @@ void Element::DetachLayoutTree(bool performing_reattach) {
   // https://crbug.com/939769
   if (ChildNeedsReattachLayoutTree() || GetComputedStyle() ||
       (!performing_reattach && IsUserActionElement())) {
-    if (!performing_reattach) {
-      UpdateCallbackSelectors(GetComputedStyle(), nullptr);
-      SetComputedStyle(nullptr);
-    }
     if (ShadowRoot* shadow_root = GetShadowRoot()) {
       shadow_root->DetachLayoutTree(performing_reattach);
       Node::DetachLayoutTree(performing_reattach);
@@ -2906,22 +2920,9 @@ void Element::DetachLayoutTree(bool performing_reattach) {
   DetachPseudoElement(kPseudoIdBackdrop, performing_reattach);
   DetachPseudoElement(kPseudoIdFirstLetter, performing_reattach);
 
-  if (HasRareData()) {
-    ElementRareData* data = GetElementRareData();
-    if (!performing_reattach)
-      data->ClearPseudoElements();
-
-    if (ElementAnimations* element_animations = data->GetElementAnimations()) {
-      if (performing_reattach) {
-        // FIXME: restart compositor animations rather than pull back to the
-        // main thread
-        element_animations->RestartAnimationOnCompositor();
-      } else {
-        element_animations->CssAnimations().Cancel();
-        element_animations->SetAnimationStyleChange(false);
-      }
-      element_animations->ClearBaseComputedStyle();
-    }
+  if (!performing_reattach) {
+    UpdateCallbackSelectors(GetComputedStyle(), nullptr);
+    SetComputedStyle(nullptr);
   }
 
   if (!performing_reattach && IsUserActionElement()) {