Add ByteArray interface and provide internal and external implementations.

runtime/vm/class_finalizer.cc

Index: runtime/vm/class_finalizer.cc
diff --git a/runtime/vm/class_finalizer.cc b/runtime/vm/class_finalizer.cc
index f6545c313cfe47faa426ab151d1ba84fe7365bc1..a7f22310909069b48e4b853010220d1bb285c8e7 100644
--- a/runtime/vm/class_finalizer.cc
+++ b/runtime/vm/class_finalizer.cc
@@ -224,9 +224,11 @@ void ClassFinalizer::VerifyBootstrapClasses() {
   cls = object_store->array_class();
   ASSERT(Array::InstanceSize() == cls.instance_size());
   cls = object_store->immutable_array_class();
-  ASSERT(Array::InstanceSize() == cls.instance_size());
-  cls = object_store->byte_buffer_class();
-  ASSERT(ByteBuffer::InstanceSize() == cls.instance_size());
+  ASSERT(ImmutableArray::InstanceSize() == cls.instance_size());
+  cls = object_store->internal_byte_array_class();
+  ASSERT(InternalByteArray::InstanceSize() == cls.instance_size());
+  cls = object_store->external_byte_array_class();
+  ASSERT(ExternalByteArray::InstanceSize() == cls.instance_size());
 #endif  // defined(DEBUG)
 
   // Remember the currently pending classes.
@@ -332,7 +334,8 @@ void ClassFinalizer::ResolveSuperType(const Class& cls) {
         (super_class.raw() == object_store->array_class()) ||
         (super_class.raw() == object_store->immutable_array_class()) ||
         (super_class.raw() == growable_object_array_class.raw()) ||
-        (super_class.raw() == object_store->byte_buffer_class()) ||
+        (super_class.raw() == object_store->internal_byte_array_class()) ||
+        (super_class.raw() == object_store->external_byte_array_class()) ||
         (super_class.raw() == integer_implementation_class.raw()) ||
         (super_class.raw() == object_store->smi_class()) ||
         (super_class.raw() == object_store->mint_class()) ||