Script: Change script/dom/{bluetooth,canvas,html} to not rely on Deref<str> for DOMString (#39480)

This is part of the future work of implementing LazyDOMString as
outlined in https://github.com/servo/servo/issues/39479.

We use str() method or direct implementations on DOMString for these
methods. We also change some types.

Signed-off-by: Narfinger <Narfinger@users.noreply.github.com>


Testing: This is essentially just renaming a method and a type and
should not change functionality.

Signed-off-by: Narfinger <Narfinger@users.noreply.github.com>

components/script/dom/html/htmliframeelement.rs

@@ -620,7 +620,7 @@ impl HTMLIFrameElementMethods<crate::DomTypeHolder> for HTMLIFrameElement {
         // Step 2: Set an attribute value given this, srcdoc's local name, and compliantString.
         element.set_attribute(
             &local_name!("srcdoc"),
-            AttrValue::String(value.as_ref().to_owned()),
+            AttrValue::String(value.str().to_owned()),
             can_gc,
         );
         Ok(())