LibWeb: Propagate body background properties to root HTML element

The Acid1 test has a bit of an unusual background - the html and body
tags have different background colors. Our painting order of the DOM was
such that the body background was painted first, then all other elements
were painted in-phase according to Appendix E of CSS 2.1. So the html
element's background color was painted over the body background.

This removes the special handling of the body background from
InitialContainingBlockBox and now all boxes are painted in-phase. Doing
this also exposed that we weren't handling Section 2.11.2 of the spec;
when the html background is unset, the body's background should be
propagated to the html element.

1 files changed, 2 insertions, 0 deletions

diff --git a/Userland/Libraries/LibWeb/HTML/HTMLHtmlElement.h b/Userland/Libraries/LibWeb/HTML/HTMLHtmlElement.h
index 2f97417a04..3e689b5a5b 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLHtmlElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLHtmlElement.h
@@ -16,6 +16,8 @@ public:
 
     HTMLHtmlElement(DOM::Document&, QualifiedName);
     virtual ~HTMLHtmlElement() override;
+
+    bool should_use_body_background_properties() const;
 };
 
 }