Revert "Revert "fix #27256, track type bounds for generic functions""

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart

Index: pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart
index ca3f810efefff793e7aeace8997be7194b3755f9..9da7da945999728a184f28531c006a079dd806dd 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/classes.dart
@@ -179,10 +179,10 @@ generic(typeConstructor, [setBaseClass]) => JS(
   return makeGenericType;
 })()''');
 
-getGenericClass(type) =>
-    JS('', '$safeGetOwnProperty($type, $_originalDeclaration)');
+getGenericClass(type) => safeGetOwnProperty(type, _originalDeclaration);
 
-getGenericArgs(type) => JS('', '$safeGetOwnProperty($type, $_typeArguments)');
+List getGenericArgs(type) =>
+    JS('List', '#', safeGetOwnProperty(type, _typeArguments));
 
 // TODO(vsm): Collapse into one expando.
 final _constructorSig = JS('', 'Symbol("sigCtor")');