fix: relax crashing DCHECK in HTMLDocumentParser

Removes an unnecessary state-assertion DCHECK. The consequences of
doing this are relatively small (since PumpTokenizer checks
IsStopped() anyway).

Bug: 901056, 1112544
Change-Id: Ie59b6d3ba34afc0de63aa3780e6ee889f8f93c81
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2366893Reviewed-by: Mason Freed <masonfreed@chromium.org>
Commit-Queue: Richard Townsend <richard.townsend@arm.com>
Cr-Commit-Position: refs/heads/master@{#800688}

third_party/blink/renderer/core/html/parser/html_document_parser.cc

@@ -448,15 +448,14 @@ void HTMLDocumentParser::DeferredPumpTokenizerIfPossible() {
   // and the parser should not be stopped, but sometimes a script completes
   // loading (so we schedule a pump) but the Document is stopped in the meantime
   // (e.g. fast/parser/iframe-onload-document-close-with-external-script.html).
-  DCHECK(task_runner_state_->GetState() ==
-             HTMLDocumentParserState::DeferredParserState::kNotScheduled ||
-         !IsStopped());
   DCHECK(task_runner_state_->GetState() ==
              HTMLDocumentParserState::DeferredParserState::kNotScheduled ||
          !IsDetached());
   TRACE_EVENT2("blink", "HTMLDocumentParser::DeferredPumpTokenizerIfPossible",
                "parser", (void*)this, "state",
                task_runner_state_->GetStateAsString());
+  if (IsStopped())
+    return;
   if (task_runner_state_->IsScheduled()) {
     HTMLDocumentParser::PumpTokenizerIfPossible();
   } else if (task_runner_state_->IsScheduledToDelayEnd()) {