[profview] Use requestAnimationFrame to schedule a render

This is more idiomatic than using a Promise.

Change-Id: I61443e90ef1c0c589284851ea9be410153919eb5
Reviewed-on: https://chromium-review.googlesource.com/c/456278Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58828}

tools/profview/profview.js

@@ -55,6 +55,7 @@ function setCallTreeState(state, callTreeState) {
 
 let main = {
   currentState : emptyState(),
+  renderPending : false,
 
   setMode(mode) {
     if (mode !== main.currentState.mode) {
@@ -197,7 +198,11 @@ let main = {
   },
 
   delayRender()  {
-    Promise.resolve().then(() => {
+    if (main.renderPending) return;
+    main.renderPending = true;
+
+    window.requestAnimationFrame(() => {
+      main.renderPending = false;
       for (let c of components) {
         c.render(main.currentState);
       }