Add an external array type to support typed arrays.

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 deac79d64b86369d519c52a5e2abc323d2406fc9..c5aa42518ffb038c9e00e0492f543583636c3391 100644
--- a/runtime/vm/class_finalizer.cc
+++ b/runtime/vm/class_finalizer.cc
@@ -215,6 +215,8 @@ void ClassFinalizer::VerifyBootstrapClasses() {
   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());
 #endif  // defined(DEBUG)
 
   // Remember the currently pending classes.
@@ -285,6 +287,7 @@ void ClassFinalizer::ResolveSuperClass(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() == integer_implementation_class.raw()) ||
         (super_class.raw() == object_store->smi_class()) ||
         (super_class.raw() == object_store->mint_class()) ||