Don't link to specific WHATWG multipage page

"Links to the multipage version of the specification are unfortunately
likely to break over time."
-- https://html.spec.whatwg.org/multipage/asefij.html

This commit removes all references to the specific pages when viewing
WHATWG using multipage mode. I went through all these links and they
redirect fine.

Regex used to generate this commit:

`s_whatwg.org/multipage/.*#_whatwg.org/multipage/#_g`

components/script/dom/htmlobjectelement.rs

@@ -87,10 +87,10 @@ impl<'a> HTMLObjectElementMethods for JSRef<'a, HTMLObjectElement> {
         ValidityState::new(window.r())
     }
 
-    // https://html.spec.whatwg.org/multipage/embedded-content.html#dom-object-type
+    // https://html.spec.whatwg.org/multipage/#dom-object-type
     make_getter!(Type);
 
-    // https://html.spec.whatwg.org/multipage/embedded-content.html#dom-object-type
+    // https://html.spec.whatwg.org/multipage/#dom-object-type
     make_setter!(SetType, "type");
 }