Do not display total percentage next to self size.

This is confusing. Calculate percentage of self size instead.

Change-Id: I2c6ef9a40dd010fbe744c18226bc461e78e6e35f
diff --git a/ui/src/frontend/flamegraph.ts b/ui/src/frontend/flamegraph.ts
index de39e1d..36923f8 100644
--- a/ui/src/frontend/flamegraph.ts
+++ b/ui/src/frontend/flamegraph.ts
@@ -259,11 +259,13 @@
 
       let selfSizeWidth = 0;
       if (this.hoveredCallsite.selfSize > 0) {
+        const selfPercentage =
+            this.hoveredCallsite.selfSize / this.totalSize * 100;
         const selfSizeText = `self: ${
             this.displaySize(
                 this.hoveredCallsite.selfSize,
                 unit,
-                unit === 'B' ? 1024 : 1000)} (${percentage.toFixed(2)}%)`;
+                unit === 'B' ? 1024 : 1000)} (${selfPercentage.toFixed(2)}%)`;
         lineSplitter = splitIfTooBig(
             selfSizeText, width, ctx.measureText(selfSizeText).width);
         selfSizeWidth = lineSplitter.lineWidth;