Reland "Roll the latest args package into the SDK repo."

This is a reland of 9906fab

Original change's description:
> Roll the latest args package into the SDK repo.
>
> Change-Id: Ie464e5c01f34a101103d16ff108b6b9eb80fbd4b
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/174485
> Reviewed-by: Nate Bosch <nbosch@google.com>
> Commit-Queue: Bob Nystrom <rnystrom@google.com>
> Auto-Submit: Bob Nystrom <rnystrom@google.com>

Change-Id: I5b7b041e02857114c257393cf9d560b6b8b03fd5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/174701
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>

.dart_tool/package_config.json

@@ -11,7 +11,7 @@
     "constraint, update this by running tools/generate_package_config.dart."
   ],
   "configVersion": 2,
-  "generated": "2020-11-15T14:18:10.587065",
+  "generated": "2020-11-30T16:23:50.740805",
   "generator": "tools/generate_package_config.dart",
   "packages": [
     {
@@ -101,7 +101,7 @@
       "name": "args",
       "rootUri": "../third_party/pkg/args",
       "packageUri": "lib/",
-      "languageVersion": "2.3"
+      "languageVersion": "2.12"
     },
     {
       "name": "async",

DEPS

@@ -68,7 +68,7 @@ vars = {
   "gperftools_revision": "180bfa10d7cb38e8b3784d60943d50e8fcef0dcb",
 
   # Revisions of /third_party/* dependencies.
-  "args_tag": "1.6.0",
+  "args_rev": "139140125126661fac88c9aa5882165936d01c91",
   "async_rev": "695b3ac280f107c84adf7488743abfdfaaeea68f",
   "bazel_worker_rev": "060c55a933d39798681a4f533b161b81dc48d77e",
   "benchmark_harness_rev": "ec6b646f5443faa871e126ac1ba248c94ca06257",
@@ -301,7 +301,7 @@ deps = {
       "@" + Var("gperftools_revision"),
 
   Var("dart_root") + "/third_party/pkg/args":
-      Var("dart_git") + "args.git" + "@" + Var("args_tag"),
+      Var("dart_git") + "args.git" + "@" + Var("args_rev"),
   Var("dart_root") + "/third_party/pkg/async":
       Var("dart_git") + "async.git" + "@" + Var("async_rev"),
   Var("dart_root") + "/third_party/pkg/bazel_worker":

pkg/native_stack_traces/bin/decode.dart

@@ -300,12 +300,12 @@ Future<void> main(List<String> arguments) async {
   if (options['help']) return print(_usages[options.command?.name]);
   if (options.command == null) return errorWithUsage('no command provided');
 
-  switch (options.command.name) {
+  switch (options.command!.name) {
     case 'help':
-      return help(options.command);
+      return help(options.command!);
     case 'find':
-      return find(options.command);
+      return find(options.command!);
     case 'translate':
-      return await translate(options.command);
+      return await translate(options.command!);
   }
 }