LibWeb: Look at both namespace & tag name in HTML parser stack checks

We were neglecting to check the namespace when looking for a specific
type of element on the stack of open elements in many cases.

This caused us to confuse HTML and SVG elements.

Tests/LibWeb/Text/expected/wpt-import/html/syntax/parsing/html5lib_namespace-sensitivity.txt

@@ -6,6 +6,6 @@ Rerun
 
 Found 1 tests
 
-1 Fail
+1 Pass
 Details
-Result	Test Name	MessageFail	html5lib_namespace-sensitivity.html de0a2051123e97a540e3aeb58375103bda021122	
+Result	Test Name	MessagePass	html5lib_namespace-sensitivity.html de0a2051123e97a540e3aeb58375103bda021122	

Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp

@@ -771,7 +771,7 @@ JS::NonnullGCPtr<DOM::Element> HTMLParser::create_element_for(HTMLToken const& t
         auto& html_element = form_associated_element->form_associated_element_to_html_element();
 
         if (m_form_element.ptr()
-            && !m_stack_of_open_elements.contains(HTML::TagNames::template_)
+            && !m_stack_of_open_elements.contains_template_element()
             && (!form_associated_element->is_listed() || !html_element.has_attribute(HTML::AttributeNames::form))
             && &intended_parent.root() == &m_form_element->root()) {
             form_associated_element->set_form(m_form_element.ptr());
@@ -1056,7 +1056,7 @@ void HTMLParser::handle_in_head(HTMLToken& token)
     // -> An end tag whose tag name is "template"
     if (token.is_end_tag() && token.tag_name() == HTML::TagNames::template_) {
         // If there is no template element on the stack of open elements, then this is a parse error; ignore the token.
-        if (!m_stack_of_open_elements.contains(HTML::TagNames::template_)) {
+        if (!m_stack_of_open_elements.contains_template_element()) {
             log_parse_error();
             return;
         }
@@ -1768,7 +1768,7 @@ void HTMLParser::handle_in_body(HTMLToken& token)
         log_parse_error();
 
         // If there is a template element on the stack of open elements, then ignore the token.
-        if (m_stack_of_open_elements.contains(HTML::TagNames::template_))
+        if (m_stack_of_open_elements.contains_template_element())
             return;
 
         // Otherwise, for each attribute on the token, check to see if the attribute is already present on the top element of the stack of open elements.
@@ -1806,7 +1806,7 @@ void HTMLParser::handle_in_body(HTMLToken& token)
         // (fragment case or there is a template element on the stack)
         if (m_stack_of_open_elements.elements().size() == 1
             || m_stack_of_open_elements.elements().at(1)->local_name() != HTML::TagNames::body
-            || m_stack_of_open_elements.contains(HTML::TagNames::template_)) {
+            || m_stack_of_open_elements.contains_template_element()) {
             return;
         }
 
@@ -1832,7 +1832,7 @@ void HTMLParser::handle_in_body(HTMLToken& token)
         // (fragment case or there is a template element on the stack)
         if (m_stack_of_open_elements.elements().size() == 1
             || m_stack_of_open_elements.elements().at(1)->local_name() != HTML::TagNames::body) {
-            VERIFY(m_parsing_fragment || m_stack_of_open_elements.contains(HTML::TagNames::template_));
+            VERIFY(m_parsing_fragment || m_stack_of_open_elements.contains_template_element());
             return;
         }
 
@@ -1986,7 +1986,7 @@ void HTMLParser::handle_in_body(HTMLToken& token)
     // -> A start tag whose tag name is "form"
     if (token.is_start_tag() && token.tag_name() == HTML::TagNames::form) {
         // If the form element pointer is not null, and there is no template element on the stack of open elements, then this is a parse error; ignore the token.
-        if (m_form_element.ptr() && !m_stack_of_open_elements.contains(HTML::TagNames::template_)) {
+        if (m_form_element.ptr() && !m_stack_of_open_elements.contains_template_element()) {
             log_parse_error();
             return;
         }
@@ -1998,7 +1998,7 @@ void HTMLParser::handle_in_body(HTMLToken& token)
 
         // Insert an HTML element for the token, and, if there is no template element on the stack of open elements, set the form element pointer to point to the element created.
         auto element = insert_html_element(token);
-        if (!m_stack_of_open_elements.contains(HTML::TagNames::template_))
+        if (!m_stack_of_open_elements.contains_template_element())
             m_form_element = verify_cast<HTMLFormElement>(*element);
         return;
     }
@@ -2163,7 +2163,7 @@ void HTMLParser::handle_in_body(HTMLToken& token)
     // -> An end tag whose tag name is "form"
     if (token.is_end_tag() && token.tag_name() == HTML::TagNames::form) {
         // If there is no template element on the stack of open elements, then run these substeps:
-        if (!m_stack_of_open_elements.contains(HTML::TagNames::template_)) {
+        if (!m_stack_of_open_elements.contains_template_element()) {
             // 1. Let node be the element that the form element pointer is set to, or null if it is not set to an element.
             auto node = m_form_element;
 
@@ -3521,7 +3521,7 @@ void HTMLParser::handle_in_table(HTMLToken& token)
 
         // If there is a template element on the stack of open elements,
         // or if the form element pointer is not null, ignore the token.
-        if (m_form_element.ptr() || m_stack_of_open_elements.contains(HTML::TagNames::template_)) {
+        if (m_form_element.ptr() || m_stack_of_open_elements.contains_template_element()) {
             return;
         }
 
@@ -3939,7 +3939,7 @@ void HTMLParser::handle_in_template(HTMLToken& token)
     // -> An end-of-file token
     if (token.is_end_of_file()) {
         // If there is no template element on the stack of open elements, then stop parsing. (fragment case)
-        if (!m_stack_of_open_elements.contains(HTML::TagNames::template_)) {
+        if (!m_stack_of_open_elements.contains_template_element()) {
             VERIFY(m_parsing_fragment);
             stop_parsing();
             return;
@@ -4316,6 +4316,9 @@ void HTMLParser::reset_the_insertion_mode_appropriately()
             node = m_stack_of_open_elements.elements().at(i).ptr();
         }
 
+        if (node->namespace_uri() != Namespace::HTML)
+            continue;
+
         if (node->local_name() == HTML::TagNames::select) {
             if (!last) {
                 for (ssize_t j = i; j > 0; --j) {

Userland/Libraries/LibWeb/HTML/Parser/StackOfOpenElements.cpp

@@ -7,6 +7,7 @@
 #include <LibWeb/DOM/Element.h>
 #include <LibWeb/HTML/Parser/HTMLParser.h>
 #include <LibWeb/HTML/Parser/StackOfOpenElements.h>
+#include <LibWeb/Namespace.h>
 
 namespace Web::HTML {
 
@@ -105,10 +106,12 @@ bool StackOfOpenElements::contains(const DOM::Element& element) const
     return false;
 }
 
-bool StackOfOpenElements::contains(FlyString const& tag_name) const
+bool StackOfOpenElements::contains_template_element() const
 {
-    for (auto& element_on_stack : m_elements) {
-        if (element_on_stack->local_name() == tag_name)
+    for (auto const& element : m_elements) {
+        if (element->namespace_uri() != Namespace::HTML)
+            continue;
+        if (element->local_name() == HTML::TagNames::template_)
             return true;
     }
     return false;
@@ -116,7 +119,7 @@ bool StackOfOpenElements::contains(FlyString const& tag_name) const
 
 void StackOfOpenElements::pop_until_an_element_with_tag_name_has_been_popped(FlyString const& tag_name)
 {
-    while (m_elements.last()->local_name() != tag_name)
+    while (m_elements.last()->namespace_uri() != Namespace::HTML || m_elements.last()->local_name() != tag_name)
         (void)pop();
     (void)pop();
 }

Userland/Libraries/LibWeb/HTML/Parser/StackOfOpenElements.h

@@ -44,12 +44,12 @@ public:
     bool has_in_scope(const DOM::Element&) const;
 
     bool contains(const DOM::Element&) const;
-    bool contains(FlyString const& tag_name) const;
+    [[nodiscard]] bool contains_template_element() const;
 
     auto const& elements() const { return m_elements; }
     auto& elements() { return m_elements; }
 
-    void pop_until_an_element_with_tag_name_has_been_popped(FlyString const&);
+    void pop_until_an_element_with_tag_name_has_been_popped(FlyString const& local_name);
 
     JS::GCPtr<DOM::Element> topmost_special_node_below(DOM::Element const&);