Make AstFactory.variableDeclaration(charOffset) a required parameter.

pkg/front_end/lib/src/fasta/builder/ast_factory.dart

Index: pkg/front_end/lib/src/fasta/builder/ast_factory.dart
diff --git a/pkg/front_end/lib/src/fasta/builder/ast_factory.dart b/pkg/front_end/lib/src/fasta/builder/ast_factory.dart
index 49baa53331179c944ddaaafe6512bf75added328..1a8a409dd44c60be365a4404db79d7944431d4ae 100644
--- a/pkg/front_end/lib/src/fasta/builder/ast_factory.dart
+++ b/pkg/front_end/lib/src/fasta/builder/ast_factory.dart
@@ -61,10 +61,9 @@ abstract class AstFactory {
   ///
   /// If the variable declaration did not have an explicitly declared type,
   /// [type] should be `null`.
-  VariableDeclaration variableDeclaration(String name,
+  VariableDeclaration variableDeclaration(String name, int charOffset,
       {DartType type,
       Expression initializer,
-      int charOffset = TreeNode.noOffset,
       int equalsCharOffset = TreeNode.noOffset,
       bool isFinal: false,
       bool isConst: false});