Revert initializing formals change in client code

client/layout/SizingFunctions.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // This file has classes representing the grid sizing functions
 
 /**
  * Represents the sizing function used for the min or max of a row or column.
  */
 // TODO(jmesserly): rename to GridSizing, or make internal
@@ skipping 21 matching lines @@
  * auto-sized.
  */
 class FixedSizing extends SizingFunction {
   final String units;
   final num length;
 
   // TODO(jmesserly): kind of ugly to have this mutable property here, but
   // we need to correctly track whether we're content sized during a layout
   bool _contentSized;
 
-  FixedSizing(this.length, [units = 'px'])
-    : super(), this.units = units,
+  FixedSizing(this.length, [this.units = 'px'])
+    : super(),
       _contentSized = false {
     if (units != 'px' && units != '%') {
       // TODO(jmesserly): support other unit types
       throw new UnsupportedOperationException('Units other than px and %');
     }
   }
 
   // TODO(jmesserly): this is only needed because of our mutable property
   FixedSizing clone() => new FixedSizing(length, units);
 
@@ skipping 86 matching lines @@
 
 class _MaxBreadthAccumulator implements _BreadthAccumulator {
   const _MaxBreadthAccumulator();
 
   void setSize(GridTrack t, num value) { t.maxBreadth = value; }
   num getSize(GridTrack t) => t.maxBreadth;
 
   SizingFunction getSizingFunction(GridTrack t) => t.maxSizing;
 }