LibWeb: Create HTMLInputElement UA shadow tree when inserted into DOM

Previously, we were creating a user-agent shadow tree when constructing
a layout tree. This meant that we did DOM manipulation (and consequently
style invalidation) during layout tree construction, which made things
very hard to reason about in Layout::TreeBuilder.

Simply everything by simply creating the UA shadow tree when the input
element inserted into a parent node instead.

1 files changed, 5 insertions, 1 deletions

diff --git a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
index cf7bd2c407..27066a9544 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
@@ -64,7 +64,6 @@ RefPtr<Layout::Node> HTMLInputElement::create_layout_node(NonnullRefPtr<CSS::Sty
     if (type() == "radio")
         return adopt_ref(*new Layout::RadioButton(document(), *this, move(style)));
 
-    create_shadow_tree_if_needed();
     auto layout_node = adopt_ref(*new Layout::BlockContainer(document(), this, move(style)));
     layout_node->set_inline(true);
     return layout_node;
@@ -284,4 +283,9 @@ String HTMLInputElement::value_sanitization_algorithm(String value) const
     return value;
 }
 
+void HTMLInputElement::inserted()
+{
+    create_shadow_tree_if_needed();
+}
+
 }