Fix corner cases of type inference with implicit references to `.call`.

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

 // Copyright (c) 2017, the Dart project authors. Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE.md file.
 
 import 'package:front_end/src/base/instrumentation.dart';
 import 'package:front_end/src/fasta/kernel/kernel_shadow_ast.dart';
+import 'package:front_end/src/fasta/names.dart' show callName;
 import 'package:front_end/src/fasta/type_inference/type_inference_engine.dart';
 import 'package:front_end/src/fasta/type_inference/type_inference_listener.dart';
 import 'package:front_end/src/fasta/type_inference/type_promotion.dart';
 import 'package:front_end/src/fasta/type_inference/type_schema.dart';
 import 'package:front_end/src/fasta/type_inference/type_schema_elimination.dart';
 import 'package:front_end/src/fasta/type_inference/type_schema_environment.dart';
 import 'package:kernel/ast.dart'
     show
         Arguments,
         AsyncMarker,
@@ skipping 212 matching lines @@
         strongMode = engine.strongMode,
         classHierarchy = engine.classHierarchy,
         instrumentation = topLevel ? null : engine.instrumentation,
         typeSchemaEnvironment = engine.typeSchemaEnvironment,
         isTopLevel = topLevel;
 
   /// Gets the type promoter that should be used to promote types during
   /// inference.
   TypePromoter get typePromoter;
 
-  FunctionType getCalleeFunctionType(
-      Member interfaceMember, DartType receiverType, Name methodName) {
+  FunctionType getCalleeFunctionType(Member interfaceMember,
+      DartType receiverType, Name methodName, bool followCall) {
     var type = getCalleeType(interfaceMember, receiverType, methodName);
     if (type is FunctionType) {
       return type;
-    } else {
-      return _functionReturningDynamic;
+    } else if (followCall && type is InterfaceType) {
+      var member = classHierarchy.getInterfaceMember(type.classNode, callName);
+      var callType = member?.getterType;
+      if (callType is FunctionType) {
+        return callType;
+      }
     }
+    return _functionReturningDynamic;
   }
 
   DartType getCalleeType(
       Member interfaceMember, DartType receiverType, Name methodName) {
     if (receiverType is InterfaceType) {
       if (interfaceMember == null) return const DynamicType();
       var memberClass = interfaceMember.enclosingClass;
       DartType calleeType;
       if (interfaceMember is Procedure) {
         if (interfaceMember.kind == ProcedureKind.Getter) {
@@ skipping 295 matching lines @@
   void _forEachArgument(
       Arguments arguments, void callback(String name, Expression expression)) {
     for (var expression in arguments.positional) {
       callback(null, expression);
     }
     for (var namedExpression in arguments.named) {
       callback(namedExpression.name, namedExpression.value);
     }
   }
 }