[maglev] Use --maglev-filter

Observe the beauty of nature, as a TODO blossoms into a DONE.

Bug: v8:7700
Change-Id: I6981a5530664aa9ba4d120000d688a682c923a23
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3622914Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80334}

src/codegen/compiler.cc

@@ -1062,8 +1062,7 @@ bool ShouldOptimize(CodeKind code_kind, Handle<SharedFunctionInfo> shared) {
     case CodeKind::TURBOFAN:
       return FLAG_opt && shared->PassesFilter(FLAG_turbo_filter);
     case CodeKind::MAGLEV:
-      // TODO(v8:7700): FLAG_maglev_filter.
-      return FLAG_maglev;
+      return FLAG_maglev && shared->PassesFilter(FLAG_maglev_filter);
     default:
       UNREACHABLE();
   }