$ diff pkg/vm/testcases/transformations/record_use/named_both.dart.json.expect pkg/compiler/test/record_use/golden/named_both.json.expect

One of the diffs:

71,76c80,85
<           "loading_unit": "1",
<           "named": {
<             "i": 2,
<             "l": 4,
<             "k": 5
<           },
---
>           "loading_unit": "out",
>           "positional": [
>             2,
>             5,
>             4
>           ],

dart2js converts the arguments to positional before the usages are recorded. We'll need to keep track of the names of named arguments (and that they were named) to be able to make dart2js emit the same info.

(Separated out from #2717)