Merge pull request #1682 from nylki/patch-1

remove incorrect info about synchronous postMessage

Author: iliakan

3-frames-and-windows/03-cross-window-communication/article.md

@@ -335,10 +335,6 @@ The full example:
 
 [codetabs src="postmessage" height=120]
 
-```smart header="There's no delay"
-There's totally no delay between `postMessage` and the `message` event. The event triggers synchronously, faster than `setTimeout(...,0)`.
-```
-
 ## Summary
 
 To call methods and access the content of another window, we should first have a reference to it.