diff --git a/interfaces/selection-api.idl b/interfaces/selection-api.idl
new file mode 100644
index 00000000000000..27efc2acbbf05a
--- /dev/null
+++ b/interfaces/selection-api.idl
@@ -0,0 +1,43 @@
+// http://w3c.github.io/selection-api/#selection-interface
+interface Selection {
+  readonly attribute Node?         anchorNode;
+  readonly attribute unsigned long anchorOffset;
+  readonly attribute Node?         focusNode;
+  readonly attribute unsigned long focusOffset;
+  readonly attribute boolean       isCollapsed;
+  readonly attribute unsigned long rangeCount;
+  readonly attribute DOMString     type;
+  Range     getRangeAt(unsigned long index);
+  void      addRange(Range range);
+  void      removeRange(Range range);
+  void      removeAllRanges();
+  void      empty();
+  void      collapse(Node? node, optional unsigned long offset = 0);
+  void      setPosition(Node? node, optional unsigned long offset = 0);
+  void      collapseToStart();
+  void      collapseToEnd();
+  void      extend(Node node, optional unsigned long offset = 0);
+  void      setBaseAndExtent(Node anchorNode,
+                             unsigned long anchorOffset,
+                             Node focusNode,
+                             unsigned long focusOffset);
+  void      selectAllChildren(Node node);
+  [CEReactions]
+  void      deleteFromDocument();
+  boolean   containsNode(Node node,
+                         optional boolean allowPartialContainment = false);
+  stringifier DOMString ();
+};
+
+partial interface Document {
+  Selection? getSelection();
+};
+
+partial interface Window {
+  Selection? getSelection();
+};
+
+partial interface GlobalEventHandlers {
+  attribute EventHandler onselectstart;
+  attribute EventHandler onselectionchange;
+};
diff --git a/selection/interfaces.html b/selection/interfaces.html
index 21b3f3e824895e..6b72f286caf9e9 100644
--- a/selection/interfaces.html
+++ b/selection/interfaces.html
@@ -5,58 +5,14 @@
 <script src=/resources/testharnessreport.js></script>
 <script src=/resources/WebIDLParser.js></script>
 <script src=/resources/idlharness.js></script>
-<script type=text/plain>
-// http://w3c.github.io/selection-api/#selection-interface
-interface Selection {
-    readonly attribute Node?         anchorNode;
-    readonly attribute unsigned long anchorOffset;
-    readonly attribute Node?         focusNode;
-    readonly attribute unsigned long focusOffset;
-    readonly attribute boolean       isCollapsed;
-    readonly attribute unsigned long rangeCount;
-    readonly attribute DOMString     type;
-    Range     getRangeAt(unsigned long index);
-    void      addRange(Range range);
-    void      removeRange(Range range);
-    void      removeAllRanges();
-    void      empty();
-    void      collapse(Node? node, optional unsigned long offset = 0);
-    void      setPosition(Node? node, optional unsigned long offset = 0);
-    void      collapseToStart();
-    void      collapseToEnd();
-    void      extend(Node node, optional unsigned long offset = 0);
-    void      setBaseAndExtent(Node anchorNode,
-                               unsigned long anchorOffset,
-                               Node focusNode,
-                               unsigned long focusOffset);
-    void      selectAllChildren(Node node);
-    [CEReactions]
-    void      deleteFromDocument();
-    boolean   containsNode(Node node,
-                           optional boolean allowPartialContainment = false);
-    stringifier DOMString ();
-};
-
-partial interface Document {
-    Selection? getSelection();
-};
-
-partial interface Window {
-    Selection? getSelection();
-};
-
-partial interface GlobalEventHandlers {
-    attribute EventHandler onselectstart;
-    attribute EventHandler onselectionchange;
-};
-</script>
 <script>
 "use strict";
 
-function doTest([dom, cssom, touchevents, uievents, html]) {
+function doTest([selection, dom, cssom, touchevents, uievents, html]) {
   var idlArray = new IdlArray();
+  idlArray.add_untested_idls('interface SVGElement {};');
   idlArray.add_untested_idls(dom + cssom + touchevents + uievents + html);
-  idlArray.add_idls(document.querySelector("script[type=text\\/plain]").textContent);
+  idlArray.add_idls(selection);
   idlArray.add_objects({Selection: ['getSelection()']});
   idlArray.test();
 }
@@ -66,7 +22,8 @@
 }
 
 promise_test(function() {
-  return Promise.all([fetchData("/interfaces/dom.idl"),
+  return Promise.all([fetchData("/interfaces/selection-api.idl"),
+                      fetchData("/interfaces/dom.idl"),
                       fetchData("/interfaces/cssom.idl"),
                       fetchData("/interfaces/touchevents.idl"),
                       fetchData("/interfaces/uievents.idl"),