[dart2js] Make diagnostic message arguments strongly typed.

We were passing arguments as just a `Map` and forcing the Message to
handle the String conversion, but the caller is much better equipped to
do it and prevents the dynamic typing.

Change-Id: Icc4ab91edf233b81a64aa3b03462b541349fa751
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149048
Reviewed-by: Sigmund Cherem <sigmund@google.com>

https://dart.googlesource.com/sdk/+/d1546cac8768101d3c6e6e15d1d56c47020fe0fe
1 file changed
tree: 10ec9af9789c642adf66ea44db57481d62506616
  1. commits.json