Retain inverted-ness when redrawing graph.

src/memray/reporters/assets/flamegraph_common.js

@@ -258,6 +258,10 @@ export function initThreadsDropdown(data, merge_threads) {
 }
 
 export function drawChart(chart_data) {
+  // In order to retain the "invertedness" when updating the graph, true
+  // by default.
+  let previouslyInverted = chart ? chart.inverted() : true;
+
   // Clear any existing chart
   if (chart) {
     chart.destroy();
@@ -270,8 +274,7 @@ export function drawChart(chart_data) {
     // smooth transitions
     .transitionDuration(250)
     .transitionEase(d3.easeCubic)
-    // invert the graph by default
-    .inverted(true)
+    .inverted(previouslyInverted)
     // make each row a little taller
     .cellHeight(20)
     // don't show elements that are less than 5px wide