Fix other.test_closure_webgpu_wasm64 (#26955)

This was broken by #26954 but not covered by CI because we run the
`other` testsuite with the emsdk version of node that doesn't support
wasm64.

Without this change the wasm64 variant complains because it tried to
case the return value of this function to a BigInt (pointer) before
returning to Wasm.

Author: sbc100

.circleci/config.yml

@@ -1081,6 +1081,7 @@ jobs:
             other.test_min_node_version
             other.test_node_emscripten_num_logical_cores
             other.test_js_base64_api
+            other.test_closure_webgpu_wasm64
             core2.test_hello_world
             core2.test_pthread_create
             core2.test_i64_invoke_bigint

src/lib/libpromise.js

@@ -274,6 +274,7 @@ addToLibrary({
   },
   emscripten_promise_await_unchecked: (id) => {
     abort('emscripten_promise_await_unchecked is only available with ASYNCIFY');
+    return 0;
   },
 #endif
 });

test/codesize/test_codesize_hello_dylink_all.json

@@ -1,7 +1,7 @@
 {
-  "a.out.js": 268222,
+  "a.out.js": 268231,
   "a.out.nodebug.wasm": 587563,
-  "total": 855785,
+  "total": 855794,
   "sent": [
     "IMG_Init",
     "IMG_Load",