Fix naming convetion:

- "Layout node" is changed to "layout spec".
- Update tests.
- Update Kittens sample.

AsyncDisplayKit/Layout/ASLayoutSpec.mm

@@ -0,0 +1,44 @@
+/*
+ *  Copyright (c) 2014-present, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the BSD-style license found in the
+ *  LICENSE file in the root directory of this source tree. An additional grant
+ *  of patent rights can be found in the PATENTS file in the same directory.
+ *
+ */
+
+#import "ASLayoutSpec.h"
+
+#import "ASAssert.h"
+#import "ASBaseDefines.h"
+
+#import "ASInternalHelpers.h"
+#import "ASLayout.h"
+
+@implementation ASLayoutSpec
+
+@synthesize spacingBefore = _spacingBefore;
+@synthesize spacingAfter = _spacingAfter;
+@synthesize flexGrow = _flexGrow;
+@synthesize flexShrink = _flexShrink;
+@synthesize flexBasis = _flexBasis;
+@synthesize alignSelf = _alignSelf;
+
++ (instancetype)new
+{
+  ASLayoutSpec *spec = [super new];
+  if (spec) {
+    spec->_flexBasis = ASRelativeDimensionUnconstrained;
+  }
+  return spec;
+}
+
+#pragma mark - Layout
+
+- (ASLayout *)calculateLayoutThatFits:(ASSizeRange)constrainedSize
+{
+  return [ASLayout newWithLayoutableObject:self size:constrainedSize.min];
+}
+
+@end