Add type inference for assert statements.

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 ac29a1e1235bc98bc1efecf2c4773b10d0320b63..15defce8b564f9fa9919fb6fd97cede25a87ac3f 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
@@ -87,6 +87,12 @@ class TypeInferenceListener
   void asExpressionExit(AsExpression expression, DartType inferredType) =>
       debugExpressionExit("asExpression", expression, inferredType);
 
+  void assertStatementEnter(AssertStatement statement) =>
+      debugStatementEnter('assertStatement', statement);
+
+  void assertStatementExit(AssertStatement statement) =>
+      debugStatementExit('assertStatement', statement);
+
   bool awaitExpressionEnter(AwaitExpression expression, DartType typeContext) =>
       debugExpressionEnter("awaitExpression", expression, typeContext);