fix propagated type of lambdas in strong mode

pkg/analyzer/test/src/task/strong/checker_test.dart

 // Copyright (c) 2015, 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 file.
 
 library analyzer.test.src.task.strong.checker_test;
 
 import '../../../reflective_tests.dart';
 import 'strong_test_helper.dart';
 
 void main() {
@@ skipping 1899 matching lines @@
   void test_implicitCasts() {
     addFile('num n; int i = /*info:ASSIGNMENT_CAST*/n;');
     check();
     // TODO(jmesserly): should not be emitting the hint as well as the error.
     // It is a "strong mode hint" however, so it will not be user visible.
     addFile(
         'num n; int i = /*info:ASSIGNMENT_CAST,error:INVALID_ASSIGNMENT*/n;');
     check(implicitCasts: false);
   }
 
+  void test_implicitCasts_genericMethods() {
+    addFile('var x = <String>[].map((x) => "");');
+    check(implicitCasts: false);
+  }
+
   void test_implicitDynamic_field() {
     addFile(r'''
 class C {
   var /*error:IMPLICIT_DYNAMIC_FIELD*/x0;
   var /*error:IMPLICIT_DYNAMIC_FIELD*/x1 = (<dynamic>[])[0];
   var /*error:IMPLICIT_DYNAMIC_FIELD*/x2,
       x3 = 42,
       /*error:IMPLICIT_DYNAMIC_FIELD*/x4;
   dynamic y0;
   dynamic y1 = (<dynamic>[])[0];
@@ skipping 1605 matching lines @@
     // Regression test for https://github.com/dart-lang/sdk/issues/25069
     checkFile('''
 typedef int Foo();
 void foo() {}
 void main () {
   Foo x = /*error:INVALID_ASSIGNMENT,info:USE_OF_VOID_RESULT*/foo();
 }
 ''');
   }
 }