Infer VariableSet types.

pkg/front_end/lib/src/fasta/kernel/kernel_ast_factory.dart

Index: pkg/front_end/lib/src/fasta/kernel/kernel_ast_factory.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_ast_factory.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_ast_factory.dart
index 54188430ea41225ea1d0b67def036da50e3840d2..d878af8372685c5ccad37cfa24ca4794d0ddb2b7 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_ast_factory.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_ast_factory.dart
@@ -249,4 +249,9 @@ class KernelAstFactory implements AstFactory<VariableDeclaration> {
     return new KernelVariableGet(variable, fact, scope)
       ..fileOffset = offsetForToken(token);
   }
+
+  @override
+  VariableSet variableSet(VariableDeclaration variable, Expression value) {
+    return new KernelVariableSet(variable, value);
+  }
 }