Adjust dot size to iterationCount (WebKit#356)

Gradually adjust scatter plot dot sizes from 5px down to 2px for iterationCount > 20.

resources/metric-ui.mjs

@@ -239,8 +239,12 @@ function renderScatterPlot({ values, width = 500, height, trackHeight, xAxisPosi
     // Axis + labels height:
     const axisHeight = 18;
     const axisMarginY = 4;
-    const markerSize = 5;
     const trackMargin = 2;
+    let markerSize = 5;
+    // Auto-adjust markers to [2px, 5px] for high iteration counts:
+    const iterationsLimit = 20;
+    if (values.length > iterationsLimit)
+        markerSize = 2 + (3 / values.length) * iterationsLimit;
     // Recalculate height:
     if (height)
         trackHeight = (height - axisHeight - axisMarginY) / trackCount;