Updates from inside componentDidMount/Update should have Task priority.

This is only observable in incremental mode.

Author: acdlite

scripts/fiber/tests-passing.txt

@@ -820,18 +820,6 @@ src/renderers/shared/fiber/__tests__/ReactIncrementalScheduling-test.js
 * splits deferred work on multiple roots
 * works on deferred roots in the order they were scheduled
 * handles interleaved deferred and animation work
-* performs animation work in animation callback
-* schedules deferred work in animation callback
-* schedules deferred work and performs animation work in animation callback
-* performs animation work and schedules deferred work in animation callback
-* performs deferred work in deferred callback if it has time
-* schedules deferred work in deferred callback if it runs out of time
-* performs animated work in deferred callback if it has time
-* performs animated work and deferred work in deferred callback if it has time
-* performs deferred and animated work work in deferred callback if it has time
-* schedules animated work in deferred callback if it runs out of time
-* schedules animated work and deferred work in deferred callback if it runs out of time
-* schedules deferred work and animated work in deferred callback if it runs out of time
 
 src/renderers/shared/fiber/__tests__/ReactIncrementalSideEffects-test.js
 * can update child nodes of a host instance
@@ -852,6 +840,7 @@ src/renderers/shared/fiber/__tests__/ReactIncrementalSideEffects-test.js
 * calls setState callback even if component bails out
 * calls componentWillUnmount after a deletion, even if nested
 * calls componentDidMount/Update after insertion/update
+* schedules sync updates when inside componentDidMount/Update
 * invokes ref callbacks after insertion/update/unmount
 * supports string refs
 

src/renderers/shared/fiber/ReactFiberScheduler.js

@@ -208,7 +208,13 @@ module.exports = function<T, P, I, TI, C>(config : HostConfig<T, P, I, TI, C>) {
     while (effectfulFiber) {
       if (effectfulFiber.effectTag & (Update | Callback)) {
         const current = effectfulFiber.alternate;
-        commitLifeCycles(current, effectfulFiber);
+        const previousPriorityContext = priorityContext;
+        priorityContext = TaskPriority;
+        try {
+          commitLifeCycles(current, effectfulFiber);
+        } finally {
+          priorityContext = previousPriorityContext;
+        }
       }
       const next = effectfulFiber.nextEffect;
       // Ensure that we clean these up so that we don't accidentally keep them.