LayoutTests/css3/flexbox/negative-margins-assert.html - WebKit - Git at Google

 <!DOCTYPE html>
 <script>
 if (window.testRunner)
     window.testRunner.dumpAsText();
 </script>
 <style>
 div {
   display: flex;
 }

 .inner {
   margin-left: -4em;
 }
 </style>

 <div>
     <div>
         <div class="inner">PASS if we don't assert</div>
     </div>
 </div>
	<!DOCTYPE html>
	<script>
	if (window.testRunner)
	window.testRunner.dumpAsText();
	</script>
	<style>
	div {
	display: flex;
	}

	.inner {
	margin-left: -4em;
	}
	</style>

	<div>
	<div>
	<div class="inner">PASS if we don't assert</div>
	</div>
	</div>