spec: Fix error in which array-like objects still throw

Author: js-choi

Diff for: spec.html

@@ -50,8 +50,7 @@ <h1><ins>Array.fromAsync ( _asyncItems_ [ , _mapfn_ [ , _thisArg_ ] ] )</ins></h
               1. Let _mapping_ be *true*.
             1. Let _usingAsyncOrSyncIterator_ be ? GetMethod(_asyncItems_, @@asyncIterator).
             1. If _usingAsyncOrSyncIterator_ is *undefined*, let _usingAsyncOrSyncIterator_ be ? GetMethod(_asyncItems_, @@iterator).
-            1. If _usingAsyncOrSyncIterator_ is *undefined*, throw a *TypeError* exception.
-            1. Else,
+            1. If _usingAsyncOrSyncIterator_ is not *undefined*, then
               1. If IsConstructor(_C_) is *true*, then
                 1. Let _A_ be ? Construct(_C_).
               1. Else,