Auto merge of #6568 - dzbarsky:delete_range, r=jdm

Implement Range#insertNode

Gecko doesn't really follow the spec but it seems to throw a HierarchyRequest error when parent is null.
Any ideas who I should talk to about fixing the spec to account for the null checks?

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tests/wpt/metadata/dom/interfaces.html.ini

@@ -252,9 +252,6 @@
   [Range interface: operation cloneContents()]
     expected: FAIL
 
-  [Range interface: operation insertNode(Node)]
-    expected: FAIL
-
   [Range interface: operation surroundContents(Node)]
     expected: FAIL
 
@@ -270,12 +267,6 @@
   [Range interface: document.createRange() must inherit property "cloneContents" with the proper type (22)]
     expected: FAIL
 
-  [Range interface: document.createRange() must inherit property "insertNode" with the proper type (23)]
-    expected: FAIL
-
-  [Range interface: calling insertNode(Node) on document.createRange() with too few arguments must throw TypeError]
-    expected: FAIL
-
   [Range interface: document.createRange() must inherit property "surroundContents" with the proper type (24)]
     expected: FAIL
 
@@ -291,12 +282,6 @@
   [Range interface: detachedRange must inherit property "cloneContents" with the proper type (22)]
     expected: FAIL
 
-  [Range interface: detachedRange must inherit property "insertNode" with the proper type (23)]
-    expected: FAIL
-
-  [Range interface: calling insertNode(Node) on detachedRange with too few arguments must throw TypeError]
-    expected: FAIL
-
   [Range interface: detachedRange must inherit property "surroundContents" with the proper type (24)]
     expected: FAIL