DevTools Timeline: fix NPE when collapsing the last group

third_party/WebKit/Source/devtools/front_end/perf_ui/FlameChart.js

Index: third_party/WebKit/Source/devtools/front_end/perf_ui/FlameChart.js
diff --git a/third_party/WebKit/Source/devtools/front_end/perf_ui/FlameChart.js b/third_party/WebKit/Source/devtools/front_end/perf_ui/FlameChart.js
index 57ddf918da548011ec884ef61ddc9ccdacabe046..49249c4e7a36bec38500e248efacfe278d1c7921 100644
--- a/third_party/WebKit/Source/devtools/front_end/perf_ui/FlameChart.js
+++ b/third_party/WebKit/Source/devtools/front_end/perf_ui/FlameChart.js
@@ -353,7 +353,7 @@ PerfUI.FlameChart = class extends PerfUI.ChartViewport {
       var timelineData = this._timelineData();
       var level = timelineData.entryLevels[this._selectedEntryIndex];
       if (this._selectedEntryIndex >= 0 && level >= group.startLevel &&
-          (groupIndex === groups.length || groups[groupIndex + 1].startLevel > level))
+          (groupIndex >= groups.length - 1 || groups[groupIndex + 1].startLevel > level))
         this._selectedEntryIndex = -1;
     }