Use highest priority lane to detect interruptions (facebook#21088)

Instead of LanePriority.

I'm removing all uses of LanePriority so I can delete it.

Author: acdlite

packages/react-reconciler/src/ReactFiberLane.new.js

@@ -334,15 +334,16 @@ export function getNextLanes(root: FiberRoot, wipLanes: Lanes): Lanes {
     // bother waiting until the root is complete.
     (wipLanes & suspendedLanes) === NoLanes
   ) {
-    getHighestPriorityLanes(wipLanes);
-    const wipLanePriority = return_highestLanePriority;
+    const nextLane = getHighestPriorityLane(nextLanes);
+    const wipLane = getHighestPriorityLane(wipLanes);
     if (
-      nextLanePriority <= wipLanePriority ||
+      // Tests whether the next lane is equal or lower priority than the wip
+      // one. This works because the bits decrease in priority as you go left.
+      nextLane >= wipLane ||
       // Default priority updates should not interrupt transition updates. The
       // only difference between default updates and transition updates is that
       // default updates do not support refresh transitions.
-      (nextLanePriority === DefaultLanePriority &&
-        wipLanePriority === TransitionPriority)
+      (nextLane === DefaultLane && (wipLane & TransitionLanes) !== NoLanes)
     ) {
       // Keep working on the existing in-progress tree. Do not interrupt.
       return wipLanes;

packages/react-reconciler/src/ReactFiberLane.old.js

@@ -334,15 +334,16 @@ export function getNextLanes(root: FiberRoot, wipLanes: Lanes): Lanes {
     // bother waiting until the root is complete.
     (wipLanes & suspendedLanes) === NoLanes
   ) {
-    getHighestPriorityLanes(wipLanes);
-    const wipLanePriority = return_highestLanePriority;
+    const nextLane = getHighestPriorityLane(nextLanes);
+    const wipLane = getHighestPriorityLane(wipLanes);
     if (
-      nextLanePriority <= wipLanePriority ||
+      // Tests whether the next lane is equal or lower priority than the wip
+      // one. This works because the bits decrease in priority as you go left.
+      nextLane >= wipLane ||
       // Default priority updates should not interrupt transition updates. The
       // only difference between default updates and transition updates is that
       // default updates do not support refresh transitions.
-      (nextLanePriority === DefaultLanePriority &&
-        wipLanePriority === TransitionPriority)
+      (nextLane === DefaultLane && (wipLane & TransitionLanes) !== NoLanes)
     ) {
       // Keep working on the existing in-progress tree. Do not interrupt.
       return wipLanes;