Update tests/js/tos.nim, make isAbsolute tested on nodejs under Windo…

…ws. (nim-lang#23377)

Windows's nodejs `isAbsolute` issue has been resolved by [this
PR](nim-lang#23365).

So we can improve the coverage for Windows.

tests/js/tos.nim

@@ -13,11 +13,9 @@ block:
   doAssert not "foo".isAbsolute
   doAssert relativePath("", "bar") == ""
   doAssert normalizedPath(".///foo//./") == "foo"
-  let cwd = getCurrentDir()
 
-  let isWindows = '\\' in cwd
-  # defined(windows) doesn't work with -d:nodejs but should
-  # these actually break because of that (see https://github.com/nim-lang/Nim/issues/13469)
-  if not isWindows:
+  when nimvm: discard
+  else:
+    let cwd = getCurrentDir()
     doAssert cwd.isAbsolute
-    doAssert relativePath(getCurrentDir() / "foo", "bar") == "../foo"
+    doAssert relativePath(getCurrentDir() / "foo", "bar") == ".." / "foo"