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/event.rs

@@ -9,7 +9,7 @@ use dom::bindings::error::Fallible;
 use dom::bindings::global::GlobalRef;
 use dom::bindings::js::{JS, MutNullableHeap, Root};
 use dom::bindings::utils::{Reflector, reflect_dom_object};
-use dom::eventtarget::{EventTarget, EventTargetHelpers};
+use dom::eventtarget::EventTarget;
 use dom::uievent::{UIEventTypeId};
 use util::str::DOMString;
 
@@ -257,18 +257,14 @@ impl<'a> EventMethods for &'a Event {
     }
 }
 
-pub trait EventHelpers {
-    fn set_trusted(self, trusted: bool);
-    fn fire(self, target: &EventTarget) -> bool;
-}
 
-impl<'a> EventHelpers for &'a Event {
-    fn set_trusted(self, trusted: bool) {
+impl Event {
+    pub fn set_trusted(&self, trusted: bool) {
         self.trusted.set(trusted);
     }
 
     // https://html.spec.whatwg.org/multipage/#fire-a-simple-event
-    fn fire(self, target: &EventTarget) -> bool {
+    pub fn fire(&self, target: &EventTarget) -> bool {
         self.set_trusted(true);
         target.dispatch_event(self)
     }