[css-inline-3][css-text-3][css-text-4] Shaping is broken by changes to vertical-align longhands #13277

The spec previously checked 'vertical-align' against 'baseline';
but actually it should have checked against the [=initial value=],
whatever that happens to be. (CSS Inline L3 expands vertical-align,
so its initial value is now more complicated to describe.)

Also clarify that baseline-source only applies to boxes that
establish an independent formatting context.

Author: fantasai

css-inline-3/Overview.bs

@@ -763,7 +763,7 @@ Alignment Baseline Source: the 'baseline-source' longhand</h4>
 	Name: baseline-source
 	Value: auto | first | last
 	Initial: auto
-	Applies to: inline-level boxes
+	Applies to: [=inline-level boxes=] that establish an [=independent formatting context=]
 	Inherited: no
 	Percentages: N/A
 	Computed value: specified keyword
@@ -3052,6 +3052,12 @@ A.3: Synthesizing Baselines for Atomic Inlines</h3>
 <h2 class="no-num" id="changes">
 Changes</h2>
 
+	Changes since the <a href="https://www.w3.org/TR/2024/WD-css-inline-3-20241218/">18 December 2024 Working Draft</a>:
+	<ul>
+		<li>Clarify that 'baseline-source' does not apply to [=inline boxes=].
+			(<a href="https://github.com/w3c/csswg-drafts/issues/13277">Issue 13277</a>)
+	</ul>
+
 	Changes since the <a href="https://www.w3.org/TR/2024/WD-css-inline-3-20240812/">12 August 2024 Working Draft</a>:
 	<ul>
 		<li>Made both values of <<text-edge>> required.

css-text-3/Overview.bs

@@ -6598,7 +6598,7 @@ Shaping Across Element Boundaries</h3>
 			</wpt>
 
 		<li>
-			'vertical-align' is not ''vertical-align/baseline''.
+			'vertical-align' is not its [=initial value=].
 
 			<wpt>
 			boundary-shaping/boundary-shaping-002.html
@@ -8407,7 +8407,10 @@ Recent Changes</h3>
 
 	The following changes have been made since
 	the <a href="https://www.w3.org/TR/2026/CRD-css-text-3-20260608/">June 2026 Candidate Recommendation Draft</a>:
-	* None yet
+	* Clarify that shaping breaks when 'vertical-align' is not its [=initial value=],
+		rather than mentioning ''vertical-align/baseline'' specifically,
+		to avoid confusion given further developments to 'vertical-align'.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/13277">Issue 13277</a>)
 
 	The following changes have been made since
 	the <a href="https://www.w3.org/TR/2024/CRD-css-text-3-20240930/">September 2024 Candidate Recommendation Draft</a>:

css-text-4/Overview.bs

@@ -11311,7 +11311,8 @@ Shaping Across Element Boundaries</h3>
 			</wpt>
 
 		<li>
-			'vertical-align' is not ''vertical-align/baseline''.
+			'vertical-align' is not its [=initial value=];
+			i.e. at least one of its [=longhands=] is not its [=initial value=].
 
 			<wpt>
 			boundary-shaping/boundary-shaping-002.html