don't produce errors from inference for downward inferred type variables

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

Index: pkg/analyzer/test/src/task/strong/checker_test.dart
diff --git a/pkg/analyzer/test/src/task/strong/checker_test.dart b/pkg/analyzer/test/src/task/strong/checker_test.dart
index ccfe62b74b83cea5cb6c3e6f5c8840432fe318c1..e976f09ccc92771bd55460271377a6d30195ecb9 100644
--- a/pkg/analyzer/test/src/task/strong/checker_test.dart
+++ b/pkg/analyzer/test/src/task/strong/checker_test.dart
@@ -2047,16 +2047,16 @@ main() {
   x = foo/*error:EXTRA_POSITIONAL_ARGUMENTS*/('1', '2', '3');
   foo/*error:NOT_ENOUGH_REQUIRED_ARGUMENTS*/(1);
   x = foo/*error:NOT_ENOUGH_REQUIRED_ARGUMENTS*/('1');
-  x = /*error:COULD_NOT_INFER*/foo/*error:EXTRA_POSITIONAL_ARGUMENTS*/(/*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/1, /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/2, 3);
-  x = /*error:COULD_NOT_INFER*/foo/*error:NOT_ENOUGH_REQUIRED_ARGUMENTS*/(/*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/1);
+  x = foo/*error:EXTRA_POSITIONAL_ARGUMENTS*/(/*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/1, /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/2, 3);
+  x = foo/*error:NOT_ENOUGH_REQUIRED_ARGUMENTS*/(/*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/1);
 
   // named arguments
   bar(y: 1, x: 2, /*error:UNDEFINED_NAMED_PARAMETER*/z: 3);
   x = bar(/*error:UNDEFINED_NAMED_PARAMETER*/z: '1', x: '2', y: '3');
   bar(y: 1);
   x = bar(x: '1', /*error:UNDEFINED_NAMED_PARAMETER*/z: 42);
-  x = /*error:COULD_NOT_INFER*/bar(/*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/y: 1, /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/x: 2, /*error:UNDEFINED_NAMED_PARAMETER*/z: 3);
-  x = /*error:COULD_NOT_INFER*/bar(/*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/x: 1);
+  x = bar(/*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/y: 1, /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/x: 2, /*error:UNDEFINED_NAMED_PARAMETER*/z: 3);
+  x = bar(/*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/x: 1);
 }
 ''');
   }