Sky: When an iframe element is removed, delete its mojo View.

sky/tests/lowlevel/iframe.sky

Index: sky/tests/lowlevel/iframe.sky
diff --git a/sky/tests/lowlevel/iframe.sky b/sky/tests/lowlevel/iframe.sky
index 2073ce66fec663af3bea631b823adc1160a2f4c9..8c3682c3a386e91c2eb75d75bc6e5d10423696fe 100644
--- a/sky/tests/lowlevel/iframe.sky
+++ b/sky/tests/lowlevel/iframe.sky
@@ -1,6 +1,12 @@
 <sky>
     <import src="../resources/dump-as-render-tree.sky" />
+    <iframe id="removeMe" src="text.sky">Should not render</iframe>
     <div>This is an <iframe style="border-style: solid; border-width: 20px" src="abarth.sky">iframe</iframe> element.</div>
     <div style="height: 200px">Placeholder.</div>
     <div>Small iframe should render <iframe style="height: 40px" src="abarth.sky">iframe</iframe> correctly.</div>
+
+    <script>
+        var removeMe = document.getElementById("removeMe");
+        removeMe.parentNode.removeChild(removeMe);
+    </script>
 </sky>