Fix form association behavior when a form and a control with form= are removed from a document toge…

LayoutTests/fast/forms/form-attribute.html

Index: LayoutTests/fast/forms/form-attribute.html
diff --git a/LayoutTests/fast/forms/form-attribute.html b/LayoutTests/fast/forms/form-attribute.html
index 5bd9dc632bdc0c306a748e72be619a9840bf2cf7..362784737d21b849ed5ea7d3a472cee43228fcda 100644
--- a/LayoutTests/fast/forms/form-attribute.html
+++ b/LayoutTests/fast/forms/form-attribute.html
@@ -180,6 +180,14 @@ shouldBe('inputElement.form', 'owner');
 shouldBe('labelElement.form', 'owner');
 
 debug('');
+debug('- Check if a form and a control are disassociated when they are removed from the document together.');
+container.innerHTML = '<div><input form=owner><form id=owner></form></div>';
+owner = document.getElementById('owner');
+shouldBe('owner.elements.length', '1');
+container.firstChild.remove();
+shouldBe('owner.elements.length', '0');
+
+debug('');
 debug('- Checks if option.form is only set if it has a &lt;select&gt; parent.');
 container.innerHTML = '<form id=firstOwner><option id=firstOption></option></form>' +
     '<form id=secondOwner><optgroup><option id=secondOption></option></optgroup></form>' +
@@ -191,6 +199,8 @@ shouldBe('option2.form', 'null');
 owner = document.getElementById('thirdOwner');
 var option3 = document.getElementById('thirdOption');
 shouldBe('option3.form', 'owner');
+
+container.remove();
 </script>
 </body>
 </html>