Tweak formatting rules. Fix #211.

lib/src/chunk.dart

Index: lib/src/chunk.dart
diff --git a/lib/src/chunk.dart b/lib/src/chunk.dart
index e0604275ae4c86cbdeb5ddc628005afd4a624187..307cd95f7de3139cee8aae18b23c040dbe9d1b46 100644
--- a/lib/src/chunk.dart
+++ b/lib/src/chunk.dart
@@ -230,9 +230,19 @@ class Cost {
   /// greater number of nested spans.
   static const normal = 1;
 
-  /// The cost of splitting after a "=" both for assignment and initialization.
+  /// Splitting after a "=" both for assignment and initialization.
   static const assignment = 2;
 
+  /// Splitting before the first argument when it happens to be a function
+  /// expression with a block body.
+  static const firstBlockArgument = 2;
+
+  /// The series of positional arguments.
+  static const positionalArguments = 2;
+
+  /// Splitting inside the brackets of a list with only one element.
+  static const singleElementList = 2;
+
   /// The cost of a single character that goes past the page limit.
   ///
   /// This cost is high to ensure any solution that fits in the page is
@@ -267,7 +277,8 @@ class SplitParam {
   final implies = <SplitParam>[];
 
   /// Creates a new [SplitParam].
-  SplitParam([this.cost = Cost.normal]);
+  SplitParam([int cost])
+      : cost = cost != null ? cost : Cost.normal;
 
   String toString() => "$id";