Only Microtask::performCheckpoint() if recursionLevel is 0

This maintains the invariant that microtask work (e.g. Mutation Observer callbacks) always occur on an empty page script stack. Previously, it was possible for a microtask to fire before the outer script had exited on document.write('<script>') or showModalDialog, etc.. R=adamk@chromium.org, adamk BUG=352181 Review URL: https://codereview.chromium.org/184043002 git-svn-id: svn://svn.chromium.org/blink/trunk@169770 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Only Microtask::performCheckpoint() if recursionLevel is 0
This maintains the invariant that microtask work (e.g. Mutation Observer callbacks) always occur on an empty page script stack. Previously, it was possible for a microtask to fire before the outer script had exited on document.write('<script>') or showModalDialog, etc.. R=adamk@chromium.org, adamk BUG=352181 Review URL: https://codereview.chromium.org/184043002 git-svn-id: svn://svn.chromium.org/blink/trunk@169770 bbb929c8-8fbe-4397-9dbb-9b2b20218538
bc8826ef · rafaelw@chromium.org · cabd8000 · bc8826ef · bc8826ef · bc8826ef
Commit bc8826ef authored Mar 21, 2014 by rafaelw@chromium.org
3 changed files
--- a/third_party/WebKit/LayoutTests/fast/dom/MutationObserver/document-write-expected.txt
+++ b/third_party/WebKit/LayoutTests/fast/dom/MutationObserver/document-write-expected.txt
+PASSED
--- a/third_party/WebKit/LayoutTests/fast/dom/MutationObserver/document-write.html
+++ b/third_party/WebKit/LayoutTests/fast/dom/MutationObserver/document-write.html
+<!DOCTYPE html>
+<head>
+</head>
+<body>
+<div id="result">RESULT</div>
+<script>
+
+var resultDiv = document.getElementById('result');
+
+if (window.testRunner) {
+    testRunner.dumpAsText();
+    testRunner.waitUntilDone();
+}
+
+var count = 0;
+
+var observer = new MutationObserver(function(r) {
+    count += r.length;
+});
+
+var div = document.createElement('div');
+observer.observe(div, { attributes: true });
+
+function mutate() {
+      div.setAttribute('count', count);
+}
+
+var counts = [];
+function check() {
+    counts.push(count);
+}
+
+function finish() {
+    setTimeout(function() {
+        check();
+
+        var result = counts[0] == 0 &&
+                     counts[1] == 0 &&
+                     counts[2] == 0 &&
+                     counts[3] == 1 ? 'PASSED' : 'FAILED';
+
+        document.documentElement.appendChild(document.createElement('body'));
+        document.body.innerHTML = result;
+        if (window.testRunner) {
+            testRunner.notifyDone();
+        }
+    }, 0);
+}
+
+finish();
+</script>
+<iframe onload="mutate(); check(); document.write('<script>check();</script>'); check(); finish();">
+</body>
--- a/third_party/WebKit/Source/core/dom/Microtask.cpp
+++ b/third_party/WebKit/Source/core/dom/Microtask.cpp
@@ -48,7 +48,7 @@ void Microtask::performCheckpoint()
 {
    V8PerIsolateData* isolateData = V8PerIsolateData::current();
    ASSERT(isolateData);
-    if (isolateData->performingMicrotaskCheckpoint())
+    if (isolateData->recursionLevel() || isolateData->performingMicrotaskCheckpoint())
        return;
    isolateData->setPerformingMicrotaskCheckpoint(true);