Reapply "reflectType() dynamic type arguments support (#26012)"

pkg/compiler/lib/src/js_backend/backend.dart

Index: pkg/compiler/lib/src/js_backend/backend.dart
diff --git a/pkg/compiler/lib/src/js_backend/backend.dart b/pkg/compiler/lib/src/js_backend/backend.dart
index 002cf4e35f99eb4b6ff63b4f9da978ac1bdbd9e6..2443fbab4d7b94c595a6aa24f8ebb63a431114ef 100644
--- a/pkg/compiler/lib/src/js_backend/backend.dart
+++ b/pkg/compiler/lib/src/js_backend/backend.dart
@@ -1987,7 +1987,7 @@ class JavaScriptBackend extends Backend {
   /**
    * Returns true if the element has to be resolved due to a mirrorsUsed
    * annotation. If we have insufficient mirrors used annotations, we only
-   * keep additonal elements if treeshaking has been disabled.
+   * keep additional elements if treeshaking has been disabled.
    */
   bool requiredByMirrorSystem(Element element) {
     return hasInsufficientMirrorsUsed && isTreeShakingDisabled ||