Set MethodInvocation.interfaceTarget during type inference.

pkg/front_end/testcases/inference/block_bodied_lambdas_basic.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 file.
 
 /*@testedFeatures=inference*/
 library test;
 
 test1() {
   List<int> o;
   var /*@type=Iterable<int>*/ y = /*@promotedType=none*/ o
-      . /*@typeArgs=int*/ map(/*@returnType=int*/ (/*@type=int*/ x) {
-    return /*@promotedType=none*/ x + 1;
+      . /*@typeArgs=int*/ /*@target=List::map*/ map(
+          /*@returnType=int*/ (/*@type=int*/ x) {
+    return /*@promotedType=none*/ x /*@target=num::+*/ + 1;
   });
   Iterable<int> z = /*@promotedType=none*/ y;
 }