Microsoft Edge 151 web platform release notes (Jul. 2026) (#3844)

* New web platform release notes for 151

* toc

* copy OT rows from 150.md

* Move features from older release notes

* Revise CSS features

* Revised the HTML features

* edit pass

* Revised the web apis section

* tod

* add 151 to firstchild nav page

* linkfix & todo

* date, en-us,

* edit pass on recent commits

* tense

* tense, pointing

* strike "improves dev experience"

* Apply suggestions from code review

Co-authored-by: Patrick Brosset <patrickbrosset@gmail.com>

* restore html

---------

Co-authored-by: captainbrosset <captainbrosset@users.noreply.github.com>
Co-authored-by: Patrick Brosset <patrick.brosset@microsoft.com>
Co-authored-by: Patrick Brosset <patrickbrosset@gmail.com>

Author: mikehoffms

microsoft-edge/toc.yml

@@ -33,7 +33,11 @@
           # latest 10
           # maint:
           # toc.yml - add new relnotes page, move a relnotes page to archive
-          # /web-platform/release-notes/index.md - add new relnotes page, remove earliest relnotes page -->
+          # /web-platform/release-notes/index.md - add new relnotes page, remove earliest relnotes page
+        - name: Microsoft Edge 151
+          href: ./web-platform/release-notes/151.md
+          displayName: Microsoft Edge 151 web platform release notes (Aug. 2026)  # page title
+
         - name: Microsoft Edge 150
           href: ./web-platform/release-notes/150.md
           displayName: Microsoft Edge 150 web platform release notes (Jul. 2026)  # page title
@@ -69,13 +73,13 @@
         - name: Microsoft Edge 142
           href: ./web-platform/release-notes/142.md
           displayName: Microsoft Edge 142 web platform release notes (Oct. 2025)  # page title
-
-        - name: Microsoft Edge 141
-          href: ./web-platform/release-notes/141.md
-          displayName: Microsoft Edge 141 web platform release notes (Oct. 2025)  # page title
         # keep 10 items above
         - name: Archive
           items:
+            - name: Microsoft Edge 141
+              href: ./web-platform/release-notes/141.md
+              displayName: Microsoft Edge 141 web platform release notes (Oct. 2025)  # page title
+
             - name: Microsoft Edge 140
               href: ./web-platform/release-notes/140.md
               displayName: Microsoft Edge 140 web platform release notes (Sep. 2025)  # page title
@@ -174,7 +178,7 @@
               # latest 10
               # maint:
               # toc.yml - add new what's new page, move a what's new page to archive
-              # /devtools/whats-new/index.md - add new what's new page, remove earliest what's new page -->
+              # /devtools/whats-new/index.md - add new what's new page, remove earliest what's new page
             - name: Microsoft Edge 149
               href: ./devtools/whats-new/149.md
               displayName: What's new in DevTools (Microsoft Edge 149)  # page title

microsoft-edge/web-platform/release-notes/147.md

@@ -49,7 +49,6 @@ To stay up-to-date and get the latest web platform features, download a preview
   * [Web Serial API on Android](#web-serial-api-on-android)
   * [WebXR Layers](#webxr-layers)
   * [WebXR Plane Detection](#webxr-plane-detection)
-  * [XML parsing in Rust for non-XSLT scenarios](#xml-parsing-in-rust-for-non-xslt-scenarios)
 * [Deprecated or removed features](#deprecated-or-removed-features)
   * [Remove inline XSLT for production of SVG](#remove-inline-xslt-for-production-of-svg)
 * [Origin trials](#origin-trials)
@@ -427,20 +426,6 @@ See also:
 * [WebXR Device API](https://developer.mozilla.org/docs/Web/API/WebXR_Device_API) at MDN.
 
 
-<!-- ------------------------------ -->
-#### XML parsing in Rust for non-XSLT scenarios
-
-Microsoft Edge now uses a Rust-based XML parser, in scenarios where XSLT processing isn't required.
-
-The Rust XML parser improves security by eliminating memory-corruption bugs in XML parsing.  This applies to:
-* The DOMParser Web API.
-* `responseXML` of `XMLHttpRequest`.
-* SVG documents.
-
-See also:
-* [DOMParser](https://developer.mozilla.org/docs/Web/API/DOMParser) at MDN.
-
-
 <!-- ====================================================================== -->
 ## Deprecated or removed features
 

microsoft-edge/web-platform/release-notes/150.md

@@ -28,7 +28,6 @@ To stay up-to-date and get the latest web platform features, download a preview
    * [Comma-separated container queries](#comma-separated-container-queries)
    * [Expose unprintable areas via CSS](#expose-unprintable-areas-via-css)
    * [Media element pseudo-classes](#media-element-pseudo-classes)
-   * [CSS `alpha()` function](#css-alpha-function)
    * [`named-feature()` function for CSS @supports](#named-feature-function-for-css-supports)
    * [`overscroll-behavior: chain`](#overscroll-behavior-chain)
    * [`flex-wrap:balance`](#flex-wrapbalance)
@@ -38,7 +37,6 @@ To stay up-to-date and get the latest web platform features, download a preview
    * [Updating all `<selectedcontent>` element in a customizable `<select>`](#updating-all-selectedcontent-element-in-a-customizable-select)
    * [Streaming out-of-order HTML](#streaming-out-of-order-html)
 * [Web APIs](#web-apis)
-   * [Expose the `FontFaceSet` interface globally](#expose-the-fontfaceset-interface-globally)
    * [Disable SVG filters on cross-origin iframes and plugins](#disable-svg-filters-on-cross-origin-iframes-and-plugins)
    * [`MediaStreamTrackProcessor` frame counters](#mediastreamtrackprocessor-frame-counters)
    * [Opaque origin for `data:` URLs](#opaque-origin-for-data-urls)
@@ -228,17 +226,6 @@ See also:
 * [`:volume-locked` CSS pseudo-class](https://developer.mozilla.org/docs/Web/CSS/Reference/Selectors/:volume-locked) at MDN.
 
 
-<!-- ------------------------------ -->
-#### CSS `alpha()` function
-
-The CSS `alpha()` function creates a new color by applying a specified alpha value to an existing color.
-
-For example, `alpha(from red / 0.5)` creates a semi-transparent red color with 50% opacity.
-
-See also:
-* [Relative Alpha Colors](https://drafts.csswg.org/css-color-5/#relative-alpha) in _CSS Color Module Level 5_.
-
-
 <!-- ------------------------------ -->
 #### `named-feature()` function for CSS `@supports`
 
@@ -357,17 +344,6 @@ See also:
 The following new Web API features are included in Microsoft Edge.
 
 
-<!-- ------------------------------ -->
-#### Expose the `FontFaceSet` interface globally
-
-Previously, the `FontFaceSet` interface was not exposed as a global property.  Chromium's interface definition language (IDL) for `FontFaceSet` previously incorrectly applied `LegacyNoInterfaceObject` to `FontFaceSet`, hiding it as a global property.
-
-This change aligns Chromium with the CSS Font Loading spec, and with Safari and Firefox.
-
-See also:
-* [FontFaceSet](https://developer.mozilla.org/docs/Web/API/FontFaceSet) at MDN.
-
-
 <!-- ------------------------------ -->
 #### Disable SVG filters on cross-origin iframes and plugins