Change CreateElementFlags CHECK => DCHECK

Bug: 1086507

Change-Id: I436c60c82bdf9214638bcc7cefb10db158705646
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2264923Reviewed-by: Mason Freed <masonfreed@chromium.org>
Commit-Queue: Dominic Farolino <dom@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782168}

third_party/blink/renderer/core/dom/create_element_flags.h

@@ -57,8 +57,7 @@ class CreateElementFlags {
         already_started_(false) {}
 
   CreateElementFlags& SetCreatedByParser(bool flag, Document* document) {
-    // TODO(crbug.com/1086507): Change this to a DCHECK.
-    CHECK(flag || !document);
+    DCHECK(flag || !document);
     created_by_parser_ = flag;
     parser_document_ = document;
     return *this;