feat: 拆分 stress benchmark 到细粒度单热点测试并修复 bench 采样逻辑

tests/stress/loop_while_index.js

@@ -0,0 +1,15 @@
+var ITERATIONS = 3000;
+
+var arr = [];
+for (var i = 0; i < 100; i++) {
+  arr.push(i);
+}
+var sum = 0;
+for (var j = 0; j < ITERATIONS; j++) {
+  var k = 0;
+  while (k < arr.length) {
+    sum += arr[k];
+    k++;
+  }
+}
+sum