[css-overflow-4] Refactor the text about block-ellipsis insertion (w3c#12872)

The text had accreted various rules and constraints, but no longer had
clear structure.

This reorganizes the whole thing in a more understandable manner.

No new behavior is introduced by this text, though some previously implicit consequences are made explicit, for clarity.

Co-authored-by: Andreu Botella <andreu@andreubotella.com>

Author: frivoal

css-overflow-4/Overview.bs

@@ -801,55 +801,93 @@ Indicating Block-Axis Overflow: the 'block-ellipsis' property</h3>
 	</dl>
 
 	When 'block-ellipsis' is neither ''no-ellipsis'' nor the empty string,
-	the <a>block overflow ellipsis</a> string
-	is wrapped in an anonymous inline
-	and placed at the end of the line box
-	as a direct child of the <a>block container</a>’s <a>root inline box</a>,
-	reducing the space in the line box
+	the [=block overflow ellipsis=] string
+	is placed at the end of the line box
+	reducing the space
 	available to the other contents of the line.
-	This inline is assigned ''unicode-bidi: plaintext''
-	and ''line-height: 0''
-	and is placed in the line box after the last
-	<a>soft wrap opportunity</a> (see [[!CSS-TEXT-3]])
-	that would still allow the entire <a>block overflow ellipsis</a> to fit on the line,
-	applying [[css-text-4#white-space-rules]] including [[css-text-4#white-space-phase-2]]
-	before inserting the [=block overflow ellipsis=].
-	For this purpose, <a>soft wrap opportunities</a> added by 'overflow-wrap' are ignored,
-	as are those inhibited by ''text-wrap-mode: nowrap''.
-	If this results in the entire contents of the line box being displaced,
-	the line box is considered to contain a [=strut=], as defined in [[CSS2/visudet#leading]].
-	Text <a href="https://www.w3.org/TR/css-text-3/#justification">alignment and justification</a>
-	occurs after placement,
-	and measures the inserted <a>block overflow ellipsis</a>
-	together with the rest of the line’s content.
 
 	<wpt>
-		block-ellipsis-001.html
-		block-ellipsis-002.html
-		block-ellipsis-003.html
-		block-ellipsis-004.html
-		block-ellipsis-005.html
-		block-ellipsis-006.html
-		block-ellipsis-010.html
-		block-ellipsis-013.html
-		block-ellipsis-014.html
-		block-ellipsis-015.tentative.html
-		block-ellipsis-016.html
-		block-ellipsis-017.html
-		block-ellipsis-018.html
 		block-ellipsis-023.html
 		block-ellipsis-024.html
-		block-ellipsis-025.html
-		block-ellipsis-026.html
-		block-ellipsis-027.html
-		block-ellipsis-028.html
+		block-ellipsis-repaint-001.html
 		block-ellipsis-repaint-003.html
 		block-ellipsis-repaint-004.html
-		block-ellipsis-repaint-001.html
-		webkit-line-clamp-014.html
-		webkit-line-clamp-025.html
-		webkit-line-clamp-032.html
-		webkit-line-clamp-035.html
+	</wpt>
+
+	More specifically:
+	* The [=block overflow ellipsis=]
+		is wrapped in an anonymous inline
+		whose parent is the [=block container=]’s [=root inline box=].
+		This inline is assigned ''unicode-bidi: plaintext''
+		and ''line-height: 0''.
+
+		<wpt>
+			block-ellipsis-002.html
+			block-ellipsis-003.html
+			block-ellipsis-004.html
+			block-ellipsis-005.html
+			block-ellipsis-006.html
+			block-ellipsis-010.html
+		</wpt>
+
+	* The user agent makes room as necessary of the [=block overflow ellipsis=]
+		by displacing content from the end of the line as if wrapping,
+		until the last <a>soft wrap opportunity</a> (see [[!CSS-TEXT-3]])
+		that would still allow the entire <a>block overflow ellipsis</a> to fit on the line,
+		applying [[css-text-4#white-space-rules]] including [[css-text-4#white-space-phase-2]]
+		before insertion.
+
+		<wpt>
+			block-ellipsis-001.html
+			block-ellipsis-028.html
+			webkit-line-clamp-025.html
+		</wpt>
+
+		For this purpose, <a>soft wrap opportunities</a> added by 'overflow-wrap' are ignored,
+		as are those inhibited by ''text-wrap-mode: nowrap''.
+
+		<wpt>
+			block-ellipsis-013.html
+			block-ellipsis-014.html
+			block-ellipsis-015.tentative.html
+			block-ellipsis-016.html
+			block-ellipsis-017.html
+			block-ellipsis-027.html
+		</wpt>
+
+		If this results in the entire contents of the line box being displaced,
+		the line box is considered to contain a [=strut=], as defined in [[CSS2/visudet#leading]].
+
+		<wpt>
+			block-ellipsis-016.html
+			block-ellipsis-018.html
+			block-ellipsis-025.html
+		</wpt>
+
+	* The anonymous inline of [=block overflow ellipsis=] is placed
+		after any remaining content,
+		after [[css-text-4#white-space-phase-2]],
+		as a direct child of the <a>block container</a>’s <a>root inline box</a>,
+		with the appropriate bidi embedding levels
+		given its directionality
+		and that of its parent.
+
+		<wpt>
+			block-ellipsis-004.html
+			block-ellipsis-005.html
+			block-ellipsis-006.html
+			block-ellipsis-026.html
+			webkit-line-clamp-014.html
+			webkit-line-clamp-032.html
+			webkit-line-clamp-035.html
+		</wpt>
+
+	Text <a href="https://www.w3.org/TR/css-text-3/#justification">alignment and justification</a>
+	occurs after placement,
+	and measures the inserted <a>block overflow ellipsis</a>
+	together with the rest of the line’s content.
+
+	<wpt>
 		webkit-line-clamp-051.html
 		webkit-line-clamp-052.html
 		webkit-line-clamp-053.html