<p dir="auto">I'm getting the following error:</p>
<p dir="auto"><code class="notranslate">Uncaught SecurityError: Blocked a frame with origin "http://localhost:8080" from accessing a frame with origin "https://w.soundcloud.com".  The frame requesting access has a protocol of "http", the frame being accessed has a protocol of "https". Protocols must match.</code></p>
<p dir="auto">I have a simple app that can display a list of sound cloud players.</p>
<p dir="auto">Steps to reproduce:</p>
<p dir="auto">Clone my repo <code class="notranslate">https://github.com/samu/vue-playground</code>, then <code class="notranslate">npm install &amp;&amp; npm run dev</code></p>
<p dir="auto">In the browser you'll see a bunch of buttons labeled with <code class="notranslate">x</code>: Click the very last one and the exception will be thrown.</p>
<h3 dir="auto">Version</h3>
<p dir="auto">2.6.14</p>
<h3 dir="auto">Reproduction link</h3>
<p dir="auto"><a href="https://codepen.io/toshirin/pen/GROapeK" rel="nofollow">codepen.io</a></p>
<h3 dir="auto">Steps to reproduce</h3>
<ol dir="auto">
<li>Go to: <a href="https://codepen.io/toshirin/pen/GROapeK" rel="nofollow">https://codepen.io/toshirin/pen/GROapeK</a></li>
<li>Type something to text box.</li>
<li>Duplicated text appears.</li>
</ol>
<p dir="auto">It may happen when initial text is empty("").If there is some text in the initial text, it doesn't happen.</p>
<h3 dir="auto">What is expected?</h3>
<p dir="auto">No duplicated text is displayed.<br>
Display the text same as I was typed.</p>
<h3 dir="auto">What is actually happening?</h3>
<p dir="auto">Duplicates text which was not typed by me is appeared.</p>
<hr>
<p dir="auto">In my investigation, I found updateChildren()'s addVnodes()(see below) causes this.<br>
<a href="https://github.com/vuejs/vue/blob/dev/src/core/vdom/patch.js#L470">https://github.com/vuejs/vue/blob/dev/src/core/vdom/patch.js#L470</a><br>
During the issue is occuring, the debbuger says:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="oldCh=[];
newCh=[&lt;vnode&gt;]; (which includes typed text)
oldStartIdx=0;
oldEndIdx=-1;"><pre class="notranslate"><code class="notranslate">oldCh=[];
newCh=[&lt;vnode&gt;]; (which includes typed text)
oldStartIdx=0;
oldEndIdx=-1;
</code></pre></div>
<p dir="auto">So L468's condition <code class="notranslate">oldStartIdx &gt; oldEndIdx</code> seem to be true.<br>
But I don't know how I fix.</p>