chore: add a benchmark testing DenseMatrix.map(...) and DenseMatrix.forEach(...) (see #3251)

test/benchmark/index.js

@@ -6,3 +6,4 @@ import './matrix_operations.js'
 import './prime.js'
 import './load.js'
 import './scope_variables.js'
+import './map.js'

test/benchmark/map.js

@@ -0,0 +1,18 @@
+import Benchmark from 'benchmark'
+import { ones } from '../../lib/esm/index.js'
+
+const denseMatrix = ones(100, 100, 'dense')
+
+new Benchmark.Suite()
+  .add('DenseMatrix.map(...)', () => {
+    denseMatrix.map(value => value)
+  })
+  .add('DenseMatrix.forEach(...)', () => {
+    denseMatrix.forEach(() => { /* noop */ })
+  })
+  .on('cycle', function (event) {
+    console.log(String(event.target))
+  })
+  .on('complete', function () {
+  })
+  .run()