[d8] Fix TestVerifySourcePositions with bound Proxy callable

Bug: chromium:1244320
Change-Id: I4472f7ffbc3f6a0ec5ca12f9e8b3501d3f0d3dc0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3133140
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76604}

src/d8/d8.cc

@@ -2012,8 +2012,14 @@ void Shell::TestVerifySourcePositions(
 
   auto callable = i::Handle<i::JSFunctionOrBoundFunction>::cast(arg_handle);
   while (callable->IsJSBoundFunction()) {
+    internal::DisallowGarbageCollection no_gc;
     auto bound_function = i::Handle<i::JSBoundFunction>::cast(callable);
     auto bound_target = bound_function->bound_target_function();
+    if (!bound_target.IsJSFunctionOrBoundFunction()) {
+      internal::AllowGarbageCollection allow_gc;
+      isolate->ThrowError("Expected function as bound target.");
+      return;
+    }
     callable =
         handle(i::JSFunctionOrBoundFunction::cast(bound_target), i_isolate);
   }