Fix IE9

packages/@glimmer/runtime/test/initial-render-test.ts

@@ -8,6 +8,22 @@ import { NodeDOMTreeConstruction } from "@glimmer/node";
 
 const XHTML_NAMESPACE = 'http://www.w3.org/1999/xhtml';
 
+const IE9_SELECT_QUIRK = (() => {
+  let select = document.createElement('select');
+  let option1 = document.createElement('option');
+  let option2 = document.createElement('option');
+  option1.setAttribute('selected', '');
+  select.appendChild(option1);
+  select.appendChild(option2);
+  document.body.appendChild(select);
+  let idx = select.selectedIndex;
+  option1.selected = false;
+  idx = select.selectedIndex;
+  let isSelectQuirk = idx === -1;
+  document.body.removeChild(select);
+  return isSelectQuirk;
+})();
+
 abstract class RenderTest extends BaseRenderTest {
   @test "HTML text content"() {
     this.render("content");
@@ -377,7 +393,13 @@ abstract class RenderTest extends BaseRenderTest {
       </select>
     `);
     selectNode = this.element.childNodes[1];
-    this.assert.equal(selectNode.selectedIndex, 0);
+
+    if (IE9_SELECT_QUIRK) {
+      this.assert.equal(selectNode.selectedIndex, -1);
+    } else {
+      this.assert.equal(selectNode.selectedIndex, 0);
+    }
+
     this.assertStableNodes();
 
     this.rerender({ selected: '' });
@@ -389,7 +411,13 @@ abstract class RenderTest extends BaseRenderTest {
       </select>
     `);
     selectNode = this.element.childNodes[1];
-    this.assert.equal(selectNode.selectedIndex, 0);
+
+    if (IE9_SELECT_QUIRK) {
+      this.assert.equal(selectNode.selectedIndex, -1);
+    } else {
+      this.assert.equal(selectNode.selectedIndex, 0);
+    }
+
     this.assertStableNodes();
 
     this.rerender({ selected: true });