Make the test work with wasm_of_ocaml

Author: vouillon

compiler/tests-jsoo/custom.wat

@@ -0,0 +1,7 @@
+; This ensures that the referenced JavaScript values are linked in the
+; runtime with separate compilation and is optimized away in case of
+; whole program compilation.
+
+(global (export "_caml_js_delete") (import "js" "caml_js_delete") anyref)
+(global (export "_process") (import "js" "process") anyref)
+(global (export "_obj") (import "js" "obj") anyref)

compiler/tests-jsoo/dune

@@ -74,7 +74,7 @@
  (js_of_ocaml
   (javascript_files custom.js))
  (wasm_of_ocaml
-  (javascript_files custom.js))
+  (javascript_files custom.js custom.wat))
  (modes js wasm))
 
 (ocamlyacc calc_parser)