Implement declarative shadow dom (#34964)

* Implement declarative shadow dom

Signed-off-by: batu_hoang <longvatrong111@gmail.com>

* Set allowDeclarativeShadowRoots false for innerHTML

Signed-off-by: batu_hoang <longvatrong111@gmail.com>

* Enable allowDeclarativeShadowRoots for Document

Signed-off-by: batu_hoang <longvatrong111@gmail.com>

* Expose HTMLTemplateElement to js

Signed-off-by: batu_hoang <longvatrong111@gmail.com>

* Implemenet setHTMLUnsafe and add more test cases

Signed-off-by: batu_hoang <longvatrong111@gmail.com>

* Declarative shadow dom: minor updates and expected test result update

Signed-off-by: batu_hoang <longvatrong111@gmail.com>

* Shadow-dom: add more test cases

Signed-off-by: batu_hoang <longvatrong111@gmail.com>

* Update comments according to the spec

Signed-off-by: batu_hoang <longvatrong111@gmail.com>

* Bump html5ever version

Signed-off-by: batu_hoang <longvatrong111@gmail.com>

---------

Signed-off-by: batu_hoang <longvatrong111@gmail.com>

components/script/dom/domimplementation.rs

@@ -174,6 +174,7 @@ impl DOMImplementationMethods<crate::DomTypeHolder> for DOMImplementation {
             None,
             Default::default(),
             false,
+            self.document.allow_declarative_shadow_roots(),
             Some(self.document.insecure_requests_policy()),
             can_gc,
         );