Using expirationTime and childExpirationTime

Related pr facebook/react#13139

Author: MQuy

src/FiberScheduler.js

@@ -52,52 +52,44 @@ export function scheduleWork(fiber, expirationTime) {
 
 function scheduleWorkToRoot(fiber, expirationTime) {
   // Update the source fiber's expiration time
-  if (
-    fiber.expirationTime === NoWork ||
-    fiber.expirationTime > expirationTime
-  ) {
+  if (fiber.expirationTime < expirationTime) {
     fiber.expirationTime = expirationTime;
   }
-  let alternate = fiber.alternate;
-  if (
-    alternate != null &&
-    (alternate.expirationTime === NoWork ||
-      alternate.expirationTime > expirationTime)
-  ) {
+  var alternate = fiber.alternate;
+  if (alternate !== null && alternate.expirationTime < expirationTime) {
     alternate.expirationTime = expirationTime;
   }
   // Walk the parent path to the root and update the child expiration time.
-  let node = fiber.return;
-  if (node == null && fiber.tag === HostRoot) {
-    return fiber.stateNode;
-  }
-  while (node != null) {
-    alternate = node.alternate;
-    if (
-      node.childExpirationTime === NoWork ||
-      node.childExpirationTime > expirationTime
-    ) {
-      node.childExpirationTime = expirationTime;
-      if (
-        alternate != null &&
-        (alternate.childExpirationTime === NoWork ||
-          alternate.childExpirationTime > expirationTime)
+  var node = fiber.return;
+  var root = null;
+  if (node === null && fiber.tag === HostRoot) {
+    root = fiber.stateNode;
+  } else {
+    while (node !== null) {
+      alternate = node.alternate;
+      if (node.childExpirationTime < expirationTime) {
+        node.childExpirationTime = expirationTime;
+        if (
+          alternate !== null &&
+          alternate.childExpirationTime < expirationTime
+        ) {
+          alternate.childExpirationTime = expirationTime;
+        }
+      } else if (
+        alternate !== null &&
+        alternate.childExpirationTime < expirationTime
       ) {
         alternate.childExpirationTime = expirationTime;
       }
-    } else if (
-      alternate != null &&
-      (alternate.childExpirationTime === NoWork ||
-        alternate.childExpirationTime > expirationTime)
-    ) {
-      alternate.childExpirationTime = expirationTime;
-    }
-    if (node.return == null && node.tag === HostRoot) {
-      return node.stateNode;
+      if (node.return === null && node.tag === HostRoot) {
+        root = node.stateNode;
+        break;
+      }
+      node = node.return;
     }
-    node = node.return;
   }
-  return null;
+
+  return root;
 }
 
 function requestWork(root, expirationTime) {