fix: add explicit return statements in benchmark functions and add method_call benchmark suite

benchmark/method_call.wren

@@ -0,0 +1,83 @@
+class Toggle {
+  this new(startState) {
+    _state = startState
+  }
+
+  value { return _state }
+  activate {
+    _state = !_state
+    return this
+  }
+}
+
+class NthToggle {
+  this new(startState, maxCounter) {
+    _state = startState
+    _countMax = maxCounter
+    _count = 0
+  }
+
+  value { return _state }
+
+  activate {
+    _count = _count + 1
+    if (_count >= _countMax) {
+      _state = !_state
+      _count = 0
+    }
+
+    return this
+  }
+}
+
+// TODO(bob): The follow the other examples, we should be using inheritance
+// here. Since Wren doesn't currently support inherited fields or calling
+// superclass constructors, it doesn't. It probably won't make a huge perf
+// difference, but it should be fixed when possible to be:
+/*
+class NthToggle is Toggle {
+  this new(startState, maxCounter) {
+    // TODO(bob): Need to distinguish superclass method calls from superclass
+    // constructor calls.
+    super.new(startState)
+    _countMax = maxCounter
+    _count = 0
+  }
+
+  activate {
+    _count = _count + 1
+    if (_count >= _countMax) {
+      _state = !_state
+      _count = 0
+    }
+
+    return this
+  }
+}
+*/
+
+var start = OS.clock
+var n = 1000000
+var i = 0
+var val = true
+var toggle = Toggle.new(val)
+
+while (i < n) {
+  val = toggle.activate.value
+  i = i + 1
+}
+
+io.write(toggle.value)
+
+val = true
+var ntoggle = NthToggle.new(val, 3)
+
+i = 0
+while (i < n) {
+  val = ntoggle.activate.value
+  i = i + 1
+}
+
+io.write(ntoggle.value)
+
+io.write("elapsed: " + (OS.clock - start).toString)