Allow summary type inference to infer a type of `void`.

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

Index: pkg/analyzer/test/src/task/strong/inferred_type_test.dart
diff --git a/pkg/analyzer/test/src/task/strong/inferred_type_test.dart b/pkg/analyzer/test/src/task/strong/inferred_type_test.dart
index b03fcce68d8ce4382e9091230756f183dcbf22b7..03567041782c7dcead4d8f428cbf5cd9c8b58343 100644
--- a/pkg/analyzer/test/src/task/strong/inferred_type_test.dart
+++ b/pkg/analyzer/test/src/task/strong/inferred_type_test.dart
@@ -4243,6 +4243,16 @@ test() {
 ''');
   }
 
+  void test_inferVariableVoid() {
+    var mainUnit = checkFile('''
+void f() {}
+var x = /*info:USE_OF_VOID_RESULT*/f();
+    ''');
+    var x = mainUnit.topLevelVariables[0];
+    expect(x.name, 'x');
+    expect(x.type.toString(), 'void');
+  }
+
   void test_instanceField_basedOnInstanceField_betweenCycles() {
     // Verify that all instance fields in one library cycle are inferred before
     // an instance fields in a dependent library cycle.