Create file index.html with this code:
<html>
<body>
<form action="index.html" method="post">
<textarea name="content">
</textarea><br>
<input type="submit" value="submit">
</form>
</body>
</html>
Open this file in Google Chrome. Enter in textarea this text
action="index.html"
and press submit button. Open Developer Tools (press Ctrl+Shift+I) and see this
<html>
<body>
<form action="about:blank" method="post">
<textarea name="content">
</textarea><br>
<input type="submit" value="submit">
</form>
</body>
</html>
Why action="index.html" replaced by action="about:blank"?
Problem exists only in Google Chrome, current version 28.0.1500.72 m.