RPP: fix extra clone of array in RendererHandler

If you enable the debug experiment, we render samples onto the UI. The
code in `RendererHandler` to do this checked `if(jsSamples)` but
`jsSamples` is an array, so this is always true.

The code within then creates a clone of `allTraceEntries` and then does
another sort on `thread.entries`, both of which we actually only want to
do if the samples _have any length_.

This CL fixes the check to ensure we don't needlessly clone the arrays.

[email protected]

Bug: 436491188
Change-Id: I9fa5e4f0bfaf542d0cf0fd1cdae0dd74825730d4
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6827313
Commit-Queue: Alina Varkki <[email protected]>
Auto-Submit: Jack Franklin <[email protected]>
Reviewed-by: Alina Varkki <[email protected]>

Author: jackfranklin

front_end/models/trace/handlers/RendererHandler.ts

@@ -343,9 +343,10 @@ export function buildHierarchy(
           allTraceEntries = allTraceEntries.concat(profileCalls);
           thread.entries = Helpers.Trace.mergeEventsInOrder(thread.entries, profileCalls);
           thread.profileCalls = profileCalls;
+
           // We'll also inject the instant JSSample events (in debug mode only)
           const jsSamples = samplesIntegrator.jsSampleEvents;
-          if (jsSamples) {
+          if (jsSamples.length) {
             allTraceEntries = [...allTraceEntries, ...jsSamples];
             thread.entries = Helpers.Trace.mergeEventsInOrder(thread.entries, jsSamples);
           }