Don't schedule descendant invalidations on display:none.

There's no need to schedule descendant invalidation sets on display:none
elements. If that element is displayed on the next lifecycle update,
RecalcStyle will make sure descendants will get their ComputedStyles if
necessary.

Bug: 972752
Change-Id: I60a980eecfccc43ff33bd4e050d223aced6383f5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1783142Reviewed-by: Eric Willigers <ericwilligers@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#693127}

third_party/blink/renderer/core/css/invalidation/pending_invalidations.cc

@@ -10,6 +10,7 @@
 #include "third_party/blink/renderer/core/dom/document.h"
 #include "third_party/blink/renderer/core/dom/element.h"
 #include "third_party/blink/renderer/core/dom/element_traversal.h"
+#include "third_party/blink/renderer/core/dom/node_computed_style.h"
 #include "third_party/blink/renderer/core/dom/shadow_root.h"
 #include "third_party/blink/renderer/core/html/html_slot_element.h"
 #include "third_party/blink/renderer/core/inspector/inspector_trace_events.h"
@@ -46,6 +47,11 @@ void PendingInvalidations::ScheduleInvalidationSetsForNode(
       if (!invalidation_set->IsEmpty())
         requires_descendant_invalidation = true;
     }
+    // No need to schedule descendant invalidations on display:none elements.
+    if (requires_descendant_invalidation && !node.GetComputedStyle() &&
+        node.CanParticipateInFlatTree()) {
+      requires_descendant_invalidation = false;
+    }
   }
 
   if (!requires_descendant_invalidation &&

third_party/blink/renderer/core/css/invalidation/pending_invalidations_test.cc

@@ -64,4 +64,24 @@ TEST_F(PendingInvalidationsTest, ScheduleOnDocumentNode) {
   EXPECT_EQ(2u, after_count - before_count);
 }
 
+TEST_F(PendingInvalidationsTest, DescendantInvalidationOnDisplayNone) {
+  GetDocument().body()->SetInnerHTMLFromString(R"HTML(
+    <style>
+      #a { display: none }
+      .a .b { color: green }
+    </style>
+    <div id="a">
+      <div class="b"></div>
+      <div class="b"></div>
+    </div>
+  )HTML");
+
+  GetDocument().View()->UpdateAllLifecyclePhases(
+      DocumentLifecycle::LifecycleUpdateReason::kTest);
+
+  // We skip scheduling descendant invalidations on display:none elements.
+  GetDocument().getElementById("a")->setAttribute(html_names::kClassAttr, "a");
+  EXPECT_FALSE(GetDocument().NeedsLayoutTreeUpdate());
+}
+
 }  // namespace blink