Outline shows incorrectly

[CYBAI]

URL: http://prismjs.com/

Scroll to the Basic Usage section and check the red outline in the code block

In Firefox Nightly:

In Servo:

Note: Servo is built from 4e6b100

Tested in macOS 10.12.6

[tigercosmos]

Might be caused by the CSS

[CYBAI]

Simplified test case

<style>
  code {
    outline: .4em solid red;
    outline-offset: .4em;
  }
</style>

<code>
  <span>
    <span>link</span>
    <span>href</span>
  </span>
</code>

Simplified test case without outline-offset

<style>
  code {
    outline: .4em solid red;
  }
</style>

<code>
  <span>
    <span>link</span>
    <span>href</span>
  </span>
</code>

[tigercosmos]

servo/components/layout/display_list/builder.rs

Lines 638 to 646 in 11edbfc

	/// Adds the display items necessary to paint the outline of this fragment to the display list
	/// if necessary.
	fn build_display_list_for_outline_if_applicable(
	&self,
	state: &mut DisplayListBuildState,
	style: &ComputedValues,
	bounds: Rect<Au>,
	clip: Rect<Au>,
	);

[dralley]

Still reproducable