Fix Flow issue from land race (facebook#34293)

A Flow upgrade removed the bundled library definitinos for
SynthaticEvent and we probably want to use our internal definitions.
Those are not properly typed at this point yet, but we can look into
that as a followup.

Author: kassens

packages/react-devtools-shared/src/devtools/views/SuspenseTab/SuspenseTimeline.js

@@ -24,6 +24,10 @@ import {TreeDispatcherContext} from '../Components/TreeContext';
 import {useHighlightHostInstance} from '../hooks';
 import {SuspenseTreeStateContext} from './SuspenseTreeContext';
 import styles from './SuspenseTimeline.css';
+import typeof {
+  SyntheticEvent,
+  SyntheticPointerEvent,
+} from 'react-dom-bindings/src/events/SyntheticEvent';
 
 // TODO: This returns the roots which would mean we attempt to suspend the shell.
 // Suspending the shell is currently not supported and we don't have a good view
@@ -126,7 +130,7 @@ export default function SuspenseTimeline(): React$Node {
     });
   }, [timeline, value]);
 
-  function handleChange(event: SyntheticEvent<HTMLInputElement>) {
+  function handleChange(event: SyntheticEvent) {
     const pendingValue = +event.currentTarget.value;
     for (let i = 0; i < timeline.length; i++) {
       const forceFallback = i > pendingValue;
@@ -164,7 +168,7 @@ export default function SuspenseTimeline(): React$Node {
     highlightHostInstance(suspense.id);
   }
 
-  function handlePointerMove(event: SyntheticPointerEvent<HTMLInputElement>) {
+  function handlePointerMove(event: SyntheticPointerEvent) {
     const bbox = inputBBox.current;
     if (bbox === null) {
       throw new Error('Bounding box of slider is unknown.');