auto merge of #1013 : huonw/servo/text-iter, r=pcwalton

And 3 other minor clean-ups: removing a redundant `if`, a redundant function call, and using `slice_from` where it is possible.

src/components/script/dom/bindings/utils.rs

@@ -775,7 +775,7 @@ pub fn FindEnumStringIndex(cx: *JSContext,
             return Err(());
         }
         let length = 0;
-        let chars = JS_GetStringCharsAndLength(cx, jsstr, ptr::to_unsafe_ptr(&length));
+        let chars = JS_GetStringCharsAndLength(cx, jsstr, &length);
         if chars.is_null() {
             return Err(());
         }