diff --git a/fixtures/attribute-behavior/AttributeTableSnapshot.md b/fixtures/attribute-behavior/AttributeTableSnapshot.md
index 89e126ba234cf..0945bff092bdf 100644
--- a/fixtures/attribute-behavior/AttributeTableSnapshot.md
+++ b/fixtures/attribute-behavior/AttributeTableSnapshot.md
@@ -648,6 +648,31 @@
 | `aria-=(null)`| (initial, warning)| `<null>` |
 | `aria-=(undefined)`| (initial, warning)| `<null>` |
 
+## `aria-hidden` (on `<div>` inside `<div>`)
+| Test Case | Flags | Result |
+| --- | --- | --- |
+| `aria-hidden=(string)`| (changed)| `"a string"` |
+| `aria-hidden=(empty string)`| (changed)| `<empty string>` |
+| `aria-hidden=(array with string)`| (changed)| `"string"` |
+| `aria-hidden=(empty array)`| (changed)| `<empty string>` |
+| `aria-hidden=(object)`| (changed)| `"result of toString()"` |
+| `aria-hidden=(numeric string)`| (changed)| `"42"` |
+| `aria-hidden=(-1)`| (changed)| `"-1"` |
+| `aria-hidden=(0)`| (changed)| `"0"` |
+| `aria-hidden=(integer)`| (changed)| `"1"` |
+| `aria-hidden=(NaN)`| (changed)| `"NaN"` |
+| `aria-hidden=(float)`| (changed)| `"99.99"` |
+| `aria-hidden=(true)`| (changed)| `"true"` |
+| `aria-hidden=(false)`| (changed)| `"false"` |
+| `aria-hidden=(string 'true')`| (changed)| `"true"` |
+| `aria-hidden=(string 'false')`| (changed)| `"false"` |
+| `aria-hidden=(string 'on')`| (changed)| `"on"` |
+| `aria-hidden=(string 'off')`| (changed)| `"off"` |
+| `aria-hidden=(symbol)`| (initial)| `<null>` |
+| `aria-hidden=(function)`| (initial)| `<null>` |
+| `aria-hidden=(null)`| (initial)| `<null>` |
+| `aria-hidden=(undefined)`| (initial)| `<null>` |
+
 ## `aria-invalidattribute` (on `<div>` inside `<div>`)
 | Test Case | Flags | Result |
 | --- | --- | --- |
@@ -5398,6 +5423,31 @@
 | `in=(null)`| (initial)| `<null>` |
 | `in=(undefined)`| (initial)| `<null>` |
 
+## `inert` (on `<div>` inside `<div>`)
+| Test Case | Flags | Result |
+| --- | --- | --- |
+| `inert=(string)`| (changed)| `<boolean: true>` |
+| `inert=(empty string)`| (changed)| `<boolean: true>` |
+| `inert=(array with string)`| (changed)| `<boolean: true>` |
+| `inert=(empty array)`| (changed)| `<boolean: true>` |
+| `inert=(object)`| (changed)| `<boolean: true>` |
+| `inert=(numeric string)`| (changed)| `<boolean: true>` |
+| `inert=(-1)`| (changed)| `<boolean: true>` |
+| `inert=(0)`| (changed)| `<boolean: true>` |
+| `inert=(integer)`| (changed)| `<boolean: true>` |
+| `inert=(NaN)`| (changed, warning)| `<boolean: true>` |
+| `inert=(float)`| (changed)| `<boolean: true>` |
+| `inert=(true)`| (initial, warning)| `<boolean: false>` |
+| `inert=(false)`| (initial, warning)| `<boolean: false>` |
+| `inert=(string 'true')`| (changed)| `<boolean: true>` |
+| `inert=(string 'false')`| (changed)| `<boolean: true>` |
+| `inert=(string 'on')`| (changed)| `<boolean: true>` |
+| `inert=(string 'off')`| (changed)| `<boolean: true>` |
+| `inert=(symbol)`| (initial, warning)| `<boolean: false>` |
+| `inert=(function)`| (initial, warning)| `<boolean: false>` |
+| `inert=(null)`| (initial)| `<boolean: false>` |
+| `inert=(undefined)`| (initial)| `<boolean: false>` |
+
 ## `in2` (on `<feBlend>` inside `<svg>`)
 | Test Case | Flags | Result |
 | --- | --- | --- |
@@ -5501,27 +5551,27 @@
 ## `inputMode` (on `<input>` inside `<div>`)
 | Test Case | Flags | Result |
 | --- | --- | --- |
-| `inputMode=(string)`| (changed)| `"a string"` |
-| `inputMode=(empty string)`| (changed)| `<empty string>` |
-| `inputMode=(array with string)`| (changed)| `"string"` |
-| `inputMode=(empty array)`| (changed)| `<empty string>` |
-| `inputMode=(object)`| (changed)| `"result of toString()"` |
-| `inputMode=(numeric string)`| (changed)| `"42"` |
-| `inputMode=(-1)`| (changed)| `"-1"` |
-| `inputMode=(0)`| (changed)| `"0"` |
-| `inputMode=(integer)`| (changed)| `"1"` |
-| `inputMode=(NaN)`| (changed, warning)| `"NaN"` |
-| `inputMode=(float)`| (changed)| `"99.99"` |
-| `inputMode=(true)`| (initial, warning)| `<null>` |
-| `inputMode=(false)`| (initial, warning)| `<null>` |
-| `inputMode=(string 'true')`| (changed)| `"true"` |
-| `inputMode=(string 'false')`| (changed)| `"false"` |
-| `inputMode=(string 'on')`| (changed)| `"on"` |
-| `inputMode=(string 'off')`| (changed)| `"off"` |
-| `inputMode=(symbol)`| (initial, warning)| `<null>` |
-| `inputMode=(function)`| (initial, warning)| `<null>` |
-| `inputMode=(null)`| (initial)| `<null>` |
-| `inputMode=(undefined)`| (initial)| `<null>` |
+| `inputMode=(string)`| (changed)| `"numeric"` |
+| `inputMode=(empty string)`| (initial)| `<empty string>` |
+| `inputMode=(array with string)`| (changed)| `"numeric"` |
+| `inputMode=(empty array)`| (initial)| `<empty string>` |
+| `inputMode=(object)`| (initial)| `<empty string>` |
+| `inputMode=(numeric string)`| (initial)| `<empty string>` |
+| `inputMode=(-1)`| (initial)| `<empty string>` |
+| `inputMode=(0)`| (initial)| `<empty string>` |
+| `inputMode=(integer)`| (initial)| `<empty string>` |
+| `inputMode=(NaN)`| (initial, warning)| `<empty string>` |
+| `inputMode=(float)`| (initial)| `<empty string>` |
+| `inputMode=(true)`| (initial, warning)| `<empty string>` |
+| `inputMode=(false)`| (initial, warning)| `<empty string>` |
+| `inputMode=(string 'true')`| (initial)| `<empty string>` |
+| `inputMode=(string 'false')`| (initial)| `<empty string>` |
+| `inputMode=(string 'on')`| (initial)| `<empty string>` |
+| `inputMode=(string 'off')`| (initial)| `<empty string>` |
+| `inputMode=(symbol)`| (initial, warning)| `<empty string>` |
+| `inputMode=(function)`| (initial, warning)| `<empty string>` |
+| `inputMode=(null)`| (initial)| `<empty string>` |
+| `inputMode=(undefined)`| (initial)| `<empty string>` |
 
 ## `integrity` (on `<script>` inside `<div>`)
 | Test Case | Flags | Result |
diff --git a/fixtures/attribute-behavior/src/attributes.js b/fixtures/attribute-behavior/src/attributes.js
index afd902d61d4c3..08d553ec5fea7 100644
--- a/fixtures/attribute-behavior/src/attributes.js
+++ b/fixtures/attribute-behavior/src/attributes.js
@@ -119,6 +119,7 @@ const attributes = [
   },
   {name: 'aria', read: getAttribute('aria')},
   {name: 'aria-', read: getAttribute('aria-')},
+  {name: 'aria-hidden', read: getProperty('ariaHidden')},
   {name: 'aria-invalidattribute', read: getAttribute('aria-invalidattribute')},
   {name: 'as', tagName: 'link'},
   {
@@ -905,7 +906,7 @@ const attributes = [
     read: getSVGProperty('height'),
     overrideStringValue: '100%',
   },
-  {name: 'hidden'},
+  {name: 'hidden', overrideStringValue: 'until-found'},
   {name: 'high', tagName: 'meter'},
   {
     name: 'horiz-adv-x',
@@ -968,6 +969,7 @@ const attributes = [
     containerTagName: 'svg',
     tagName: 'feBlend',
   },
+  {name: 'inert'},
   {
     name: 'in2',
     read: getSVGProperty('in2'),
@@ -977,7 +979,7 @@ const attributes = [
   {name: 'initialChecked', read: getAttribute('initialchecked')},
   {name: 'initialValue', read: getAttribute('initialvalue')},
   {name: 'inlist', read: getAttribute('inlist')},
-  {name: 'inputMode', tagName: 'input', read: getAttribute('inputmode')}, // TODO: Should use property but it's not implemented in Chrome
+  {name: 'inputMode', tagName: 'input', overrideStringValue: 'numeric'},
   {name: 'integrity', tagName: 'script'},
   {
     name: 'intercept',