Fix https rdata fuzzer

Forgot to update it to not try to cast to service type without checking
for malformed.

Fixed: 1145485,1145466
Bug: 1138620
Change-Id: Ifee9b59a4678ffe607dc9cc21cdd456e3675a53f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2520138
Auto-Submit: Eric Orth <ericorth@chromium.org>
Commit-Queue: Dan McArdle <dmcardle@chromium.org>
Reviewed-by: Dan McArdle <dmcardle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824221}

net/dns/https_record_rdata_fuzzer.cc

@@ -32,9 +32,10 @@ void ParseAndExercise(base::StringPiece data) {
 
   CHECK_EQ(parsed->Type(), dns_protocol::kTypeHttps);
   if (parsed->IsAlias()) {
+    CHECK(!parsed->IsMalformed());
     AliasFormHttpsRecordRdata* alias = parsed->AsAliasForm();
     alias->alias_name();
-  } else {
+  } else if (!parsed->IsMalformed()) {
     ServiceFormHttpsRecordRdata* service = parsed->AsServiceForm();
     CHECK_GT(service->priority(), 0);
     service->service_name();