url: reslove urls with . and ..

'.' and '..' are directory specs and resloving urls with or without
the hostname with '.' and '..' should add a trailing slash to the
end of the url.

Fix nodejs#8992

lib/url.js

@@ -629,8 +629,8 @@ Url.prototype.resolveObject = function(relative) {
   // then it must NOT get a trailing slash.
   var last = srcPath.slice(-1)[0];
   var hasTrailingSlash = (
-      (result.host || relative.host) && (last === '.' || last === '..') ||
-      last === '');
+      (result.host || relative.host || srcPath.length > 1) &&
+      (last === '.' || last === '..') || last === '');
 
   // strip single dots, resolve double dots to parent dir
   // if the path tries to go above the root, `up` ends up > 0

test/simple/test-url.js

@@ -1112,6 +1112,14 @@ var relativeTests = [
   ['/foo/bar/baz/', 'quux/baz', '/foo/bar/baz/quux/baz'],
   ['/foo/bar/baz', '../../../../../../../../quux/baz', '/quux/baz'],
   ['/foo/bar/baz', '../../../../../../../quux/baz', '/quux/baz'],
+  ['/foo', '.', '/'],
+  ['/foo', '..', '/'],
+  ['/foo/', '.', '/foo/'],
+  ['/foo/', '..', '/'],
+  ['/foo/bar', '.', '/foo/'],
+  ['/foo/bar', '..', '/'],
+  ['/foo/bar/', '.', '/foo/bar/'],
+  ['/foo/bar/', '..', '/foo/'],
   ['foo/bar', '../../../baz', '../../baz'],
   ['foo/bar/', '../../../baz', '../baz'],
   ['http://example.com/b//c//d;p?q#blarg', 'https:#hash2', 'https:///#hash2'],