Add type inference for `this` expressions.

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

Index: pkg/front_end/lib/src/fasta/kernel/kernel_field_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_field_builder.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_field_builder.dart
index d7c9b7d06ff0a5439913ca3449fa149ee50880a8..7c04220e3b0eda0b1143a1a3d0bcb1fe749d6d92 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_field_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_field_builder.dart
@@ -73,8 +73,8 @@ class KernelFieldBuilder extends FieldBuilder<Expression> {
       // should it be the part URI?
       var typeInferenceEngine = library.loader.typeInferenceEngine;
       var listener = new TypeInferenceListener();
-      var typeInferrer =
-          typeInferenceEngine.createTopLevelTypeInferrer(field, listener);
+      var typeInferrer = typeInferenceEngine.createTopLevelTypeInferrer(
+          listener, field.enclosingClass?.thisType, field);
       var bodyBuilder = new BodyBuilder(
           library,
           this,