Bug 1650105 - Emit error (not warning) for HTML4/XHTML1 doctype. DONTBUILD NPOTB r=alchen

Since 2594493 HTML4/XHTML1 doctypes have caused the warning `Obsolete doctype. Expected <!DOCTYPE html>`. This change makes that message an error rather than just a warning — bringing the parser into conformance with whatwg/html@31c20af (whatwg/html#2049). Differential Revision: https://phabricator.services.mozilla.com/D82028
2020-07-06 12:45:18 +00:00 · 2020-07-06 12:45:18 +00:00 · 23655261b6
--- a/parser/html/javasrc/TreeBuilder.java
+++ b/parser/html/javasrc/TreeBuilder.java
@ -768,7 +768,7 @@ public abstract class TreeBuilder<T> implements TokenHandler,
                                systemIdentifier))

                ) {
-                    warn("Obsolete doctype. Expected \u201C<!DOCTYPE html>\u201D.");
+                    err("Obsolete doctype. Expected \u201C<!DOCTYPE html>\u201D.");
                } else if (!((systemIdentifier == null || Portability.literalEqualsString(
                        "about:legacy-compat", systemIdentifier)) && publicIdentifier == null)) {
                    err("Legacy doctype. Expected \u201C<!DOCTYPE html>\u201D.");