Report geometric mean of averages.

Before we used to compute the geometric mean of all samples as time and
then turn that into rate, which is confusing since it doesn't match the
intuition (and the definition) of geometric mean of rates.

src/bootstrap.js

@@ -136,11 +136,7 @@ suite.forEach(benchmark => {
 
 suite.on("complete", event => {
   if (suite.aborted) return;
-  const sample = [];
-  suite.forEach(benchmark => {
-    sample.push(...benchmark.stats.sample);
-  });
-  const hz = 1 / gmean(sample);
+  const hz = gmean(suite.map(benchmark => benchmark.hz));
   displayResultMessage("geomean", `${hz.toFixed(2)}`, "highlighted-result");
 
   const statusDiv = document.getElementById("status");

src/cli.js

@@ -53,11 +53,7 @@ suite.on("cycle", event => {
 
 suite.on("complete", event => {
   if (suite.aborted) return;
-  const sample = [];
-  suite.forEach(benchmark => {
-    sample.push(...benchmark.stats.sample);
-  });
-  const hz = 1 / gmean(sample);
+  const hz = gmean(suite.map(benchmark => benchmark.hz));
   console.log("--------------------------------------");
   console.log(`Geometric mean: ${align(hz.toFixed(2), 5, "right")} runs/sec`);
 });