Use custom type helpers for HTMLPortalElement.

Bug: 1040627
Change-Id: If4f98b2269a0266ea9c56630a7f968d5b04af2b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2013486
Commit-Queue: Jeremy Roman <jbroman@chromium.org>
Reviewed-by: Mason Freed <masonfreed@chromium.org>
Cr-Commit-Position: refs/heads/master@{#734161}

third_party/blink/renderer/build/scripts/make_element_lookup_trie.py

@@ -43,6 +43,7 @@ class ElementLookupTrieWriter(json5_generator.Writer):
         'interfaceHeaderDir': {},
         'interfaceName': {},
         'noConstructor': {},
+        'noTypeHelpers': {},
         'runtimeEnabled': {},
     }
     default_metadata = {

third_party/blink/renderer/core/html/html_element.h

@@ -109,6 +109,7 @@ class CORE_EXPORT HTMLElement : public Element {
 
   virtual bool IsHTMLUnknownElement() const { return false; }
   virtual bool IsPluginElement() const { return false; }
+  virtual bool IsHTMLPortalElement() const { return false; }
 
   // https://html.spec.whatwg.org/C/#category-label
   virtual bool IsLabelable() const;

third_party/blink/renderer/core/html/html_tag_names.json5

@@ -363,6 +363,9 @@
       interfaceName: "HTMLPortalElement",
       interfaceHeaderDir: "third_party/blink/renderer/core/html/portal",
       runtimeEnabled: "Portals",
+      // Portals could be enabled in some documents but not others (due to
+      // origin trials), so we need custom type helpers.
+      noTypeHelpers: true,
     },
     "pre",
     {

third_party/blink/renderer/core/html/portal/html_portal_element.h

@@ -14,6 +14,7 @@
 #include "third_party/blink/renderer/core/core_export.h"
 #include "third_party/blink/renderer/core/dom/node.h"
 #include "third_party/blink/renderer/core/html/html_frame_owner_element.h"
+#include "third_party/blink/renderer/platform/wtf/casting.h"
 
 namespace blink {
 
@@ -39,6 +40,8 @@ class CORE_EXPORT HTMLPortalElement : public HTMLFrameOwnerElement {
           portal_client_receiver = {});
   ~HTMLPortalElement() override;
 
+  bool IsHTMLPortalElement() const final { return true; }
+
   // ScriptWrappable overrides.
   void Trace(Visitor* visitor) override;
 
@@ -132,6 +135,20 @@ class CORE_EXPORT HTMLPortalElement : public HTMLFrameOwnerElement {
   bool was_just_adopted_ = false;
 };
 
+// Type casting. Custom since adoption could lead to an HTMLPortalElement ending
+// up in a document that doesn't have Portals enabled.
+template <>
+struct DowncastTraits<HTMLPortalElement> {
+  static bool AllowFrom(const HTMLElement& element) {
+    return element.IsHTMLPortalElement();
+  }
+  static bool AllowFrom(const Node& node) {
+    if (const HTMLElement* html_element = DynamicTo<HTMLElement>(node))
+      return html_element->IsHTMLPortalElement();
+    return false;
+  }
+};
+
 }  // namespace blink
 
 #endif  // THIRD_PARTY_BLINK_RENDERER_CORE_HTML_PORTAL_HTML_PORTAL_ELEMENT_H_

third_party/blink/renderer/core/page/focus_controller.cc

@@ -49,6 +49,7 @@
 #include "third_party/blink/renderer/core/html/forms/text_control_element.h"
 #include "third_party/blink/renderer/core/html/html_plugin_element.h"
 #include "third_party/blink/renderer/core/html/html_slot_element.h"
+#include "third_party/blink/renderer/core/html/portal/html_portal_element.h"
 #include "third_party/blink/renderer/core/html_names.h"
 #include "third_party/blink/renderer/core/input/event_handler.h"
 #include "third_party/blink/renderer/core/layout/hit_test_result.h"