script: Do not call "scroll into view" when handling element clicks (#39326)

Previously, when we click any element, it would trigger "scroll into
view". What's worse, for an anchor `<a>`, clicking it would "scroll into
view" instead of navigating to the url until you retry the click. The
reason is that we built `scrollIntoView` into the focus transaction
system with default option. However, the default `preventScroll` for
`FocusOption` is false according to spec, which triggers "scroll into
view" by default with focus triggered by interaction.

This PR
1. Adds spec document for those which really expects "scroll into view",
i.e. `<form>` when validating data.
2. Make sure when we begin focus transaction, we prevent "scroll into
view".
3. `Focus` method of element/document stays unchanged, which by default
scroll into view if no parameter provided according to spec.


Testing: Manually tested on `servo.org` and other websites, and examples
with `<form>` still correctly scroll into view when validation fails.
Fixes: #38616

---------

Signed-off-by: Euclid Ye <yezhizhenjiakang@gmail.com>

components/script/dom/document.rs

@@ -1161,7 +1161,9 @@ impl Document {
         *self.focus_transaction.borrow_mut() = Some(FocusTransaction {
             element: self.focused.get().as_deref().map(Dom::from_ref),
             has_focus: self.has_focus.get(),
-            focus_options: FocusOptions::default(),
+            focus_options: FocusOptions {
+                preventScroll: true,
+            },
         });
     }
 
@@ -1199,7 +1201,14 @@ impl Document {
         focus_initiator: FocusInitiator,
         can_gc: CanGc,
     ) {
-        self.request_focus_with_options(elem, focus_initiator, FocusOptions::default(), can_gc);
+        self.request_focus_with_options(
+            elem,
+            focus_initiator,
+            FocusOptions {
+                preventScroll: true,
+            },
+            can_gc,
+        );
     }
 
     /// Request that the given element receive focus once the current