fn.dart shouldn't spam the log

sky/framework/fn.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 library fn;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:sky' as sky;
 import 'reflect.dart' as reflect;
 
-bool _checkedMode;
+bool _initIsInCheckedMode() {
+  void testFn(double i) {}
+  try {
+    testFn('not a double');
+  } catch (ex) {
+    return true;
+  }
+  return false;
+}
 
-bool _debugWarnings() {
-  void testFn(double i) {}
-
-  if (_checkedMode == null) {
-    _checkedMode = false;
-    try {
-      testFn('not a double');
-    } catch (ex) {
-      _checkedMode = true;
-    }
-  }
-
-  return _checkedMode;
-}
+final bool _isInCheckedMode = _initIsInCheckedMode();
+final bool _shouldLogRenderDuration = false;
 
 class EventHandler {
   final String type;
   final sky.EventListener listener;
 
   EventHandler(this.type, this.listener);
 }
 
 class EventMap {
   final List<EventHandler> _handlers = new List<EventHandler>();
@@ skipping 107 matching lines @@
     Object key,
     List<Node> children,
     Style style,
 
     this.inlineStyle
   }) : super(key:key) {
 
     _className = style == null ? '': style._className;
     _children = children == null ? _emptyList : children;
 
-    if (_debugWarnings()) {
+    if (_isInCheckedMode) {
       _debugReportDuplicateIds();
     }
   }
 
   void _remove() {
     super._remove();
     if (_children != null) {
       for (var child in _children) {
         child._remove();
       }
@@ skipping 343 matching lines @@
 void _renderDirtyComponents() {
   Stopwatch sw = new Stopwatch()..start();
 
   _dirtyComponents.sort((a, b) => a._order - b._order);
   for (var comp in _dirtyComponents) {
     comp._renderIfDirty();
   }
 
   _dirtyComponents.clear();
   _renderScheduled = false;
+
   sw.stop();
-  print("Render took ${sw.elapsedMicroseconds} microseconds");
+  if (_shouldLogRenderDuration)
+    print("Render took ${sw.elapsedMicroseconds} microseconds");
 }
 
 void _scheduleComponentForRender(Component c) {
   _dirtyComponents.add(c);
 
   if (!_renderScheduled) {
     _renderScheduled = true;
     new Future.microtask(_renderDirtyComponents);
   }
 }
@@ skipping 108 matching lines @@
       _dirty = true;
       _scheduleComponentForRender(this);
     }
   }
 
   Node render();
 }
 
 abstract class App extends Component {
   sky.Node _host = null;
-  App()
-    : super(stateful: true) {
-
+  App() : super(stateful: true) {
     _host = sky.document.createElement('div');
     sky.document.appendChild(_host);
 
     new Future.microtask(() {
       Stopwatch sw = new Stopwatch()..start();
+
       _sync(null, _host, null);
       assert(_root is sky.Node);
+
       sw.stop();
-      print("Initial render: ${sw.elapsedMicroseconds} microseconds");
+      if (_shouldLogRenderDuration)
+        print("Initial render: ${sw.elapsedMicroseconds} microseconds");
     });
   }
 }