Make ResizeObserver and IntersectionObserver timing match other browsers

https://bugs.webkit.org/show_bug.cgi?id=245946 Reviewed by Simon Fraser. Run IntersectionObservers after ResizeObservers to match Blink and Gecko. Imported the test from web-platform-tests/wpt#36216 * LayoutTests/imported/w3c/web-platform-tests/resize-observer/ordering-expected.txt: Added. * LayoutTests/imported/w3c/web-platform-tests/resize-observer/ordering.html: Added. * Source/WebCore/page/Page.cpp: (WebCore::Page::updateRendering): Canonical link: https://commits.webkit.org/255132@main
WebKit · Oct 4, 2022 · 565a28303653d49dcb47855db613dcdbcf9519be · 565a283
1 parent e289f6f
commit 565a28303653d49dcb47855db613dcdbcf9519be
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diff --git a/LayoutTests/imported/w3c/web-platform-tests/resize-observer/ordering-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/resize-observer/ordering-expected.txt
@@ -0,0 +1,3 @@
+
+PASS ResizeObserver and IntersectionObserver ordering
+
diff --git a/LayoutTests/imported/w3c/web-platform-tests/resize-observer/ordering.html b/LayoutTests/imported/w3c/web-platform-tests/resize-observer/ordering.html
@@ -0,0 +1,25 @@
+<!doctype html>
+<title>ResizeObserver and IntersectionObserver ordering</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+  async_test(function(t) {
+    let sawResize = false;
+    let sawIo = false;
+    let resizeObserver = new ResizeObserver(t.step_func(function() {
+      assert_false(sawIo, "ResizeObserver notification should be delivered before IntersectionObserver notification");
+      sawResize = true;
+      resizeObserver.disconnect();
+    }));
+
+    let io = new IntersectionObserver(t.step_func_done(function() {
+      assert_true(sawResize, "IntersectionObserver notification should be delivered after ResizeObserver notification");
+      sawIo = true;
+      io.disconnect();
+    }));
+
+    resizeObserver.observe(document.documentElement);
+    io.observe(document.documentElement);
+  });
+</script>
+
diff --git a/Source/WebCore/page/Page.cpp b/Source/WebCore/page/Page.cpp
@@ -1688,14 +1688,14 @@ void Page::updateRendering()
 
     layoutIfNeeded();
 
-    runProcessingStep(RenderingUpdateStep::IntersectionObservations, [] (Document& document) {
-        document.updateIntersectionObservations();
-    });
-
     runProcessingStep(RenderingUpdateStep::ResizeObservations, [&] (Document& document) {
         document.updateResizeObservations(*this);
     });
 
+    runProcessingStep(RenderingUpdateStep::IntersectionObservations, [] (Document& document) {
+        document.updateIntersectionObservations();
+    });
+
     runProcessingStep(RenderingUpdateStep::Images, [] (Document& document) {
         for (auto& image : document.cachedResourceLoader().allCachedSVGImages()) {
             if (auto* page = image->internalPage())