Add find ref as a bench test

Author: liufengyun

tests/bench/FindRef.scala

@@ -0,0 +1,11 @@
+class MyInt(val x: Int) {
+  def eq(that: MyInt): Boolean = this.x == that.x
+}
+
+class Test {
+  def foo(x: MyInt, y: MyInt): Boolean = x.eq(y)
+
+  val a = MyInt(2)
+  val b = MyInt(3)
+  foo(a, b)
+}