refactor: import rollup

src/util/url.js

@@ -1,5 +1,4 @@
-import resolveUrl from 'resolve-url'
-import _ from './underscore'
+import {last, isArray} from './underscore'
 
 const splitPathRe = /^(\/?|)([\s\S]*?)((?:\.{1,2}|[^/]+?|)(\.[^./]*|))(?:[/]*)$/
 const urlRe = /^(?:\w+:)?\/\/([^\s.]+\.\S{2}|localhost[:?\d]*)\S*$/
@@ -15,11 +14,28 @@ export function valid (path) {
 }
 
 export function resolve (root, path) {
-  if (Object.prototype.toString.call(root) === '[object Array]') {
+  if (isArray(root)) {
     root = root[0]
   }
-  if (root && _.last(root) !== '/') {
+  if (root && last(root) !== '/') {
     root += '/'
   }
   return resolveUrl(root, path)
 }
+
+function resolveUrl (root, path) {
+  const base = document.createElement('base')
+  base.href = arguments[0]
+
+  const head = document.getElementsByTagName('head')[0]
+  head.insertBefore(base, head.firstChild)
+
+  const a = document.createElement('a')
+  a.href = path
+  const resolved = a.href
+  base.href = resolved
+
+  head.removeChild(base)
+
+  return resolved
+}