Remove helper traits

Now that JSRef<T> is gone, there is no need to have helper traits.

On components/script/*.rs:

    # Remove imports.
    /^ *use dom::[a-z]+::\{.*Helpers/ {
        s/\{(Raw[^L]|[^L][^a])[a-zA-Z]+Helpers, /\{/
        s/, (Raw[^L]|[^L][^a])[a-zA-Z]+Helpers([,}])/\2/g
        s/\{([a-zA-Z]+)\}/\1/
        /\{\}/d
        s/::self;$/;/
    }
    /^ *use dom::[a-z]+::\{?(Raw[^L]|[^L][^a])[a-zA-Z]+Helpers\}?;$/d

On components/script/dom/*.rs:

    # Ignore layout things.
    /^(pub )?(impl|trait).*Layout.* \{/,/^}$/ { P; D; }

    # Delete helpers traits.
    /^(pub )?trait ([^L][^ ]|L[^a])[^ ]+Helpers(<'a>)? \{$/,/^\}$/D

    # Patch private helpers.
    /^impl.*Private.*Helpers/,/^\}$/ {
        s/^impl<'a> Private([^L][^ ]|L[^a])[^ ]+Helpers(<'a>)? for &'a ([^ ]+) \{$/impl \3 {/
        /^ *(unsafe )?fn .*\(self.*[<&]'a/ {
            s/&'a /\&/g
            s/<'a, /</g
        }
        /^ *(unsafe )?fn /s/\(self([,)])/\(\&self\1/
    }

    # Patch public helpers.
    /^impl.*Helpers/,/^\}$/ {
        s/^impl(<'a>)? ([^L][^ ]|L[^a])[^ ]+Helpers(<'a>)? for (&'a )?([^ ]+) \{$/impl \5 {/
        /^ *(unsafe )?fn .*\(self.*[<&]'a/ {
            s/&'a /\&/g
            s/<'a, /</g
        }
        /^ *(unsafe )?fn .*\(&?self[,)]/s/(unsafe )?fn/pub &/
        /^ *pub (unsafe )?fn /s/\(self([,)])/\(\&self\1/
    }

The few error cases were then fixed by hand.

components/script/dom/attr.rs

@@ -234,17 +234,9 @@ impl<'a> AttrMethods for &'a Attr {
     }
 }
 
-pub trait AttrHelpers<'a> {
-    fn set_value(self, set_type: AttrSettingType, value: AttrValue, owner: &Element);
-    fn value(self) -> Ref<'a, AttrValue>;
-    fn local_name(self) -> &'a Atom;
-    fn set_owner(self, owner: Option<&Element>);
-    fn owner(self) -> Option<Root<Element>>;
-    fn summarize(self) -> AttrInfo;
-}
 
-impl<'a> AttrHelpers<'a> for &'a Attr {
-    fn set_value(self, set_type: AttrSettingType, value: AttrValue, owner: &Element) {
+impl Attr {
+    pub fn set_value(&self, set_type: AttrSettingType, value: AttrValue, owner: &Element) {
         assert!(Some(owner) == self.owner().r());
 
         let node = NodeCast::from_ref(owner);
@@ -263,17 +255,17 @@ impl<'a> AttrHelpers<'a> for &'a Attr {
         }
     }
 
-    fn value(self) -> Ref<'a, AttrValue> {
+    pub fn value(&self) -> Ref<AttrValue> {
         self.value.borrow()
     }
 
-    fn local_name(self) -> &'a Atom {
+    pub fn local_name(&self) -> &Atom {
         &self.local_name
     }
 
     /// Sets the owner element. Should be called after the attribute is added
     /// or removed from its older parent.
-    fn set_owner(self, owner: Option<&Element>) {
+    pub fn set_owner(&self, owner: Option<&Element>) {
         let ref ns = self.namespace;
         match (self.owner().r(), owner) {
             (None, Some(new)) => {
@@ -289,11 +281,11 @@ impl<'a> AttrHelpers<'a> for &'a Attr {
         self.owner.set(owner.map(JS::from_ref))
     }
 
-    fn owner(self) -> Option<Root<Element>> {
+    pub fn owner(&self) -> Option<Root<Element>> {
         self.owner.get().map(Root::from_rooted)
     }
 
-    fn summarize(self) -> AttrInfo {
+    pub fn summarize(&self) -> AttrInfo {
         let Namespace(ref ns) = self.namespace;
         AttrInfo {
             namespace: (**ns).to_owned(),