script: Reduce the use of `unsafe` in LayoutDom (#31979)

Remove the use of unsafe code in the layout wrappers of the DOM. The
main change here is that `unsafe_get()` no longer needs to be an unsafe
method, which allows us to transitively remove or reduce unsafe blocks
from callers. The function itself is not renamed, because it's still
a bit dangerous to start removing the layers of abstraction from actual
DOM nodes.

In addition `init_style_and_opaque_layout_data` can be merged into
`initialize_data`, which removes one more unsafe method.

Finally, a "Safety" section is added to some unsafe methods.

1 files changed, 2 insertions, 3 deletions

diff --git a/components/script/dom/htmlinputelement.rs b/components/script/dom/htmlinputelement.rs
index 5ebd9c2cdc0..44669e7f875 100755
--- a/components/script/dom/htmlinputelement.rs
+++ b/components/script/dom/htmlinputelement.rs
@@ -1000,7 +1000,7 @@ impl<'dom> LayoutDom<'dom, HTMLInputElement> {
     }
 
     fn input_type(self) -> InputType {
-        unsafe { self.unsafe_get().input_type.get() }
+        self.unsafe_get().input_type.get()
     }
 
     fn textinput_sorted_selection_offsets_range(self) -> Range<UTF8Bytes> {
@@ -1054,9 +1054,8 @@ impl<'dom> LayoutHTMLInputElementHelpers<'dom> for LayoutDom<'dom, HTMLInputElem
         }
     }
 
-    #[allow(unsafe_code)]
     fn size_for_layout(self) -> u32 {
-        unsafe { self.unsafe_get().size.get() }
+        self.unsafe_get().size.get()
     }
 
     fn selection_for_layout(self) -> Option<Range<usize>> {