Infer VariableSet types.

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

Index: pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
index 48a7845160516d20b6cb907503d7d3b92afba579..1c6bf7d38c4ed92918a40355749249939353b633 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
@@ -884,3 +884,17 @@ class KernelVariableGet extends VariableGet implements KernelExpression {
     });
   }
 }
+
+/// Concrete shadow object representing a write to a variable in kernel form.
+class KernelVariableSet extends VariableSet implements KernelExpression {
+  KernelVariableSet(VariableDeclaration variable, Expression value)
+      : super(variable, value);
+
+  @override
+  DartType _inferExpression(
+      KernelTypeInferrer inferrer, DartType typeContext, bool typeNeeded) {
+    var variable = this.variable as KernelVariableDeclaration;
+    return inferrer.inferVariableSet(
+        typeContext, typeNeeded, variable._declaredType, value);
+  }
+}