dart:typed_data type hierarchy changes try 3

sdk/lib/_internal/compiler/implementation/js_backend/native_emitter.dart

Index: sdk/lib/_internal/compiler/implementation/js_backend/native_emitter.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_backend/native_emitter.dart b/sdk/lib/_internal/compiler/implementation/js_backend/native_emitter.dart
index 13cc42b9cab04eb484b4db8e810383084580cb5f..8a2ab78ca2e963a6d8bafe774f77a257f958ef15 100644
--- a/sdk/lib/_internal/compiler/implementation/js_backend/native_emitter.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_backend/native_emitter.dart
@@ -105,11 +105,25 @@ class NativeEmitter {
     return backend.namer.isolateAccess(element);
   }
 
-  List<String> nativeTagsOfClass(ClassElement cls) {
+  // The tags string contains comma-separated 'words' which are either dispatch
+  // tags (having JavaScript identifier syntax) and directives that begin with
+  // `!`.
+  List<String> nativeTagsOfClassRaw(ClassElement cls) {
     String quotedName = cls.nativeTagInfo.slowToString();
     return quotedName.substring(1, quotedName.length - 1).split(',');
   }
 
+  List<String> nativeTagsOfClass(ClassElement cls) {
+    return nativeTagsOfClassRaw(cls).where((s) => !s.startsWith('!')).toList();
+  }
+
+  bool nativeHasTagsMarker(ClassElement cls, String marker) {
+    return nativeTagsOfClassRaw(cls).contains(marker);
+  }
+
+  bool nativeForcedNonLeaf(ClassElement cls) =>
+      nativeHasTagsMarker(cls, '!nonleaf');
+
   /**
    * Writes the class definitions for the interceptors to [mainBuffer].
    * Writes code to associate dispatch tags with interceptors to [nativeBuffer].
@@ -197,6 +211,10 @@ class NativeEmitter {
       } else if (extensionPoints.containsKey(classElement)) {
         needed = true;
       }
+      if (classElement.isNative() && nativeForcedNonLeaf(classElement)) {
+        needed = true;
+        nonleafClasses.add(classElement);
+      }
 
       if (needed || neededClasses.contains(classElement)) {
         neededClasses.add(classElement);