Performance tracks are sorted by start time

To ensure that parent comes first we subtrack a little bit when we bubble
the start time.

Author: sebmarkbage

packages/react-reconciler/src/ReactProfilerTimer.js

@@ -90,8 +90,13 @@ function popComponentEffectStart(prevEffectStart: number): void {
   if (!enableProfilerTimer || !enableProfilerCommitHooks) {
     return;
   }
-  // If the parent component didn't have a start time, we let this current time persist.
-  if (prevEffectStart >= 0) {
+  if (prevEffectStart < 0) {
+    // If the parent component didn't have a start time, we use the start
+    // of the child as the parent's start time. We subtrack a minimal amount of
+    // time to ensure that the parent's start time is before the child to ensure
+    // that the performance tracks line up in the right order.
+    componentEffectStartTime -= 0.001;
+  } else {
     // Otherwise, we restore the previous parent's start time.
     componentEffectStartTime = prevEffectStart;
   }