Infer VariableSet types.

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 d6ba3266fef99542c4e17a4d769ec3607976d845..ec853d80e39dd0db99b2bea4a147d49cb99ebb4f 100644
--- a/pkg/front_end/lib/src/fasta/builder/ast_factory.dart
+++ b/pkg/front_end/lib/src/fasta/builder/ast_factory.dart
@@ -186,4 +186,7 @@ abstract class AstFactory<V> {
   /// Creates a read of a local variable.
   VariableGet variableGet(VariableDeclaration variable,
       TypePromotionFact<V> fact, TypePromotionScope scope, Token token);
+
+  /// Creates a write of a local variable.
+  VariableSet variableSet(VariableDeclaration variable, Expression value);
 }