Fix test and add skynet example.

example/skynet.wren

@@ -0,0 +1,27 @@
+// A million fiber microbenchmark based on: https://github.com/atemerev/skynet.
+class Skynet {
+  static makeFiber(num, size, div) {
+    return Fiber.new {
+      if (size == 1) {
+        Fiber.yield(num)
+      } else {
+        var fibers = []
+        for (i in 0...div) {
+          var subNum = num + i * (size / div)
+          fibers.add(makeFiber(subNum, size / div, div))
+        }
+
+        var sum = 0
+        for (task in fibers) {
+          sum = sum + task.call()
+        }
+        Fiber.yield(sum)
+      }
+    }
+  }
+}
+
+var start = System.clock
+var result = Skynet.makeFiber(0, 1000000, 10).call()
+var end = System.clock
+System.print("Result: %(result) in %(end - start) s")