Update preprocessor to "support" instant events

These are no-ops for us, but adding recognition of the event type will prevent profiles imported from e.g. Chrome Canary from thorwing with an "unrecognized event" error. (This will resolve issue #20767.)

Author: Brian Vaughn

packages/react-devtools-scheduling-profiler/src/import-worker/preprocessData.js

@@ -390,6 +390,9 @@ function processTimelineEvent(
     // TODO: Begin user timing measure
   } else if (ph === 'e') {
     // TODO: End user timing measure
+  } else if (ph === 'i' || ph === 'I') {
+    // Instant events.
+    // Note that the capital "I" is a deprecated value that exists in Chrome Canary traces.
   } // eslint-disable-line brace-style
 
   // Unrecognized event