[torque] Only allow basic type expressions in class extends clause

Bug: v8:7793
Change-Id: If419ec5659e98ebeba454417d097a7981ac3da65
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1596729Reviewed-by: Simon Zünd <szuend@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61238}

src/torque/torque-parser.cc

@@ -578,6 +578,9 @@ base::Optional<ParseResult> MakeClassDeclaration(
     NamingConventionError("Type", name->value, "UpperCamelCase");
   }
   auto extends = child_results->NextAs<base::Optional<TypeExpression*>>();
+  if (extends && !BasicTypeExpression::DynamicCast(*extends)) {
+    ReportError("Expected type name in extends clause.");
+  }
   auto generates = child_results->NextAs<base::Optional<std::string>>();
   auto methods = child_results->NextAs<std::vector<Declaration*>>();
   auto fields = child_results->NextAs<std::vector<ClassFieldExpression>>();