diff --git a/testing/web-platform/tests/html/semantics/popovers/popover-invoking-attribute.tentative.html b/testing/web-platform/tests/html/semantics/popovers/popover-invoking-attribute.tentative.html
index 5ce315ef1d9ea..b49bb4e4a34ce 100644
--- a/testing/web-platform/tests/html/semantics/popovers/popover-invoking-attribute.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popovers/popover-invoking-attribute.tentative.html
@@ -34,6 +34,10 @@
     return el;
   };
 }
+function setInvokingContentAttribute(invoker,attr,idref) {
+  invoker.setAttribute(attr,idref);
+  assert_equals(invoker[attr + "Element"],document.getElementById(idref));
+}
 const supportedButtonTypes = ['button','reset','submit',''].map(type => {
   return   {
     name: `<button type="${type}">`,
@@ -85,13 +89,13 @@
                 assert_not_equals(popover1.id,popover2.id);
                 const invoker = testcase.makeElement(test);
                 if (use_idl) {
-                  invoker.popoverToggleTarget = t===1 ? popover1.id : (t===2 ? popover2.id : null);
-                  invoker.popoverShowTarget = s===1 ? popover1.id : (s===2 ? popover2.id : null);
-                  invoker.popoverHideTarget = h===1 ? popover1.id : (h===2 ? popover2.id : null);
+                  invoker.popoverToggleTargetElement = t===1 ? popover1 : (t===2 ? popover2 : null);
+                  invoker.popoverShowTargetElement = s===1 ? popover1 : (s===2 ? popover2 : null);
+                  invoker.popoverHideTargetElement = h===1 ? popover1 : (h===2 ? popover2 : null);
                 } else {
-                  if (t) invoker.setAttribute('popovertoggletarget',t===1 ? popover1.id : popover2.id);
-                  if (s) invoker.setAttribute('popovershowtarget',s===1 ? popover1.id : popover2.id);
-                  if (h) invoker.setAttribute('popoverhidetarget',h===1 ? popover1.id : popover2.id);
+                  if (t) setInvokingContentAttribute(invoker,'popoverToggleTarget',t===1 ? popover1.id : popover2.id);
+                  if (s) setInvokingContentAttribute(invoker,'popoverShowTarget',s===1 ? popover1.id : popover2.id);
+                  if (h) setInvokingContentAttribute(invoker,'popoverHideTarget',h===1 ? popover1.id : popover2.id);
                 }
                 assert_true(!document.getElementById(popover1.id));
                 assert_true(!document.getElementById(popover2.id));
diff --git a/testing/web-platform/tests/html/semantics/popovers/popover-top-layer-combinations.tentative.html b/testing/web-platform/tests/html/semantics/popovers/popover-top-layer-combinations.tentative.html
index 0e04f30481be3..001bf88a25ef8 100644
--- a/testing/web-platform/tests/html/semantics/popovers/popover-top-layer-combinations.tentative.html
+++ b/testing/web-platform/tests/html/semantics/popovers/popover-top-layer-combinations.tentative.html
@@ -119,7 +119,7 @@
       document.body.appendChild(button);
       assert_equals(ex.id,'');
       ex.id = 'popover-id';
-      button.popoverToggleTarget = ex.id;
+      button.popoverToggleTargetElement = ex;
       assert_true(ex.matches(':closed'));
       await clickOn(button);
       ensureIsOpenPopover(ex,'Invoking element should be able to invoke all popovers');
diff --git a/testing/web-platform/tests/interfaces/popover.tentative.idl b/testing/web-platform/tests/interfaces/popover.tentative.idl
index 3d7fdcffa82f9..7e38b1f09ac9a 100644
--- a/testing/web-platform/tests/interfaces/popover.tentative.idl
+++ b/testing/web-platform/tests/interfaces/popover.tentative.idl
@@ -6,11 +6,9 @@ partial interface HTMLElement {
 };
 
 interface mixin PopoverTargetElement {
-  // TODO(crbug.com/1405856): These might change to `Element`, or additional
-  // attributes like `popoverToggleTargetElement` might be added for that.
-  [CEReactions] attribute DOMString? popoverToggleTarget;
-  [CEReactions] attribute DOMString? popoverHideTarget;
-  [CEReactions] attribute DOMString? popoverShowTarget;
+  [CEReactions] attribute Element? popoverToggleTargetElement;
+  [CEReactions] attribute Element? popoverHideTargetElement;
+  [CEReactions] attribute Element? popoverShowTargetElement;
 };
 HTMLInputElement includes PopoverTargetElement;
 HTMLButtonElement includes PopoverTargetElement;