fix(hash): Properly handle encoded parameters in hash (close vuejs#2725)

Fix an issue where page browsing to a route and then reloading leads to
inconsistent parameters and fullPath values.

Author: isra17

src/history/hash.js

@@ -107,27 +107,15 @@ function ensureSlash (): boolean {
 }
 
 export function getHash (): string {
-  // We can't use window.location.hash here because it's not
-  // consistent across browsers - Firefox will pre-decode it!
+  // We need to get the raw hash to keep consistent behavior with routes
+  // `fullPath` using encoded path. The params are decoded later in the
+  // matcher.
   let href = window.location.href
   const index = href.indexOf('#')
   // empty path
   if (index < 0) return ''
 
   href = href.slice(index + 1)
-  // decode the hash but not the search or hash
-  // as search(query) is already decoded
-  // https://github.com/vuejs/vue-router/issues/2708
-  const searchIndex = href.indexOf('?')
-  if (searchIndex < 0) {
-    const hashIndex = href.indexOf('#')
-    if (hashIndex > -1) {
-      href = decodeURI(href.slice(0, hashIndex)) + href.slice(hashIndex)
-    } else href = decodeURI(href)
-  } else {
-    href = decodeURI(href.slice(0, searchIndex)) + href.slice(searchIndex)
-  }
-
   return href
 }