Auto merge of #8255 - frewsxcv:rm-font-face-attribute-field, r=eefriedman

Remove struct field for <font> 'face' attribute

Part of #7863

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components/script/dom/htmlfontelement.rs

@@ -4,7 +4,6 @@
 
 use cssparser::RGBA;
 use dom::attr::{Attr, AttrValue};
-use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::HTMLFontElementBinding;
 use dom::bindings::codegen::Bindings::HTMLFontElementBinding::HTMLFontElementMethods;
 use dom::bindings::conversions::Castable;
@@ -23,7 +22,6 @@ use util::str::{self, DOMString, parse_legacy_font_size};
 pub struct HTMLFontElement {
     htmlelement: HTMLElement,
     color: Cell<Option<RGBA>>,
-    face: DOMRefCell<Option<Atom>>,
 }
 
 
@@ -32,7 +30,6 @@ impl HTMLFontElement {
         HTMLFontElement {
             htmlelement: HTMLElement::new_inherited(localName, prefix, document),
             color: Cell::new(None),
-            face: DOMRefCell::new(None),
         }
     }
 
@@ -82,11 +79,6 @@ impl VirtualMethods for HTMLFontElement {
                     str::parse_legacy_color(&value).ok()
                 }));
             },
-            &atom!(face) => {
-                *self.face.borrow_mut() =
-                    mutation.new_value(attr)
-                            .map(|value| value.as_atom().clone())
-            },
             _ => {},
         }
     }
@@ -111,10 +103,11 @@ impl HTMLFontElement {
 
     #[allow(unsafe_code)]
     pub fn get_face(&self) -> Option<Atom> {
-        let face = unsafe { self.face.borrow_for_layout() };
-        match *face {
-            Some(ref s) => Some(s.clone()),
-            None => None,
+        unsafe {
+            self.upcast::<Element>()
+                .get_attr_for_layout(&ns!(""), &atom!("face"))
+                .map(AttrValue::as_atom)
+                .cloned()
         }
     }