wasm/iframe-postmessage.html timeouts often on GTK. Latest run results: TPPPPPPPPPPPTPPPPTPPTPPPTPPPPPTTTPPPPPPPTPTPPPPTTPTPPPPPTPTPPPTPTPPPTTPTPPPPTPPPTPTTPPTPPPPPTPPTPTPT
The test(s) filed under this bug have been consistently passing for the last 4000 revisions. Marking bug as fixed. Committed r263254: <https://trac.webkit.org/changeset/263254>