Plug more leaks

All good now.
diff --git a/src/hb-blob.cc b/src/hb-blob.cc
index cdb7496..17ff339 100644
--- a/src/hb-blob.cc
+++ b/src/hb-blob.cc
@@ -126,7 +126,7 @@
 {
   hb_blob_t *blob;
 
-  if (!length || offset >= parent->length || !(blob = hb_object_create<hb_blob_t> ()))
+  if (!length || offset >= parent->length)
     return &_hb_blob_nil;
 
   hb_blob_make_immutable (parent);