Implement type inference for "not" expressions.

pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart

Index: pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart
diff --git a/pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart b/pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart
index 62a25442bd54c9f11cf8a5609a8d9f289c391fbc..190652ed5f84583535ecb02bb1abeaf7655a88d8 100644
--- a/pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart
+++ b/pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart
@@ -200,6 +200,12 @@ class TypeInferenceListener
           MethodInvocation expression, DartType inferredType) =>
       debugExpressionExit("methodInvocation", expression, inferredType);
 
+  bool notEnter(Not expression, DartType typeContext) =>
+      debugExpressionEnter("not", expression, typeContext);
+
+  void notExit(Not expression, DartType inferredType) =>
+      debugExpressionExit("not", expression, inferredType);
+
   bool nullLiteralEnter(NullLiteral expression, DartType typeContext) =>
       debugExpressionEnter("nullLiteral", expression, typeContext);