Erroneous CLI arguments passed through to `dart compile js` call.

[natebosch]

https://github.com/dart-lang/test/actions/runs/16611570855/job/47163483168?pr=2526

test/runner/precompiled_test.dart: browser tests (setUpAll) (failed)

Process `/opt/hostedtoolcache/dart/3.10.0-43.0.dev/x64/bin/dart compile js --executable_name=/opt/hostedtoolcache/dart/3.10.0-43.0.dev/x64/bin/dart --mark_main_isolate_as_system_isolate --packages=/home/runner/work/test/test/.dart_tool/package_config.json /tmp/browser_testPDBZPX/precompiled.dart --out=precompiled/test.dart.browser_test.dart.js` exited with exitCode 1. Output:
    Compile Dart to JavaScript.
-------------8<-----------------
    
    Error: Unknown option '--executable_name=/opt/hostedtoolcache/dart/3.10.0-43.0.dev/x64/bin/dart'.

This coming through Platform.executableArguments. We also get a --mark_main_isolate_as_system_isolate which doesn't make sense passed to dart compile js.

test/pkgs/test/test/runner/precompiled_test.dart

Line 275 in 6aeb1e4

...Platform.executableArguments,

These arguments started getting forwarded during the null safety migration, so I think it's safe to drop now.