[css-text-4] Improve wording of preserve-auto

Author: fantasai

css-text-4/Overview.bs

@@ -69,19 +69,11 @@ White Space Collapsing: the 'text-space-collapse' property</h3>
 		<dt><dfn>preserve-auto</dfn>
 		<dd>
 			This value preserves white space and <a>segment breaks</a> as for ''preserve''.
-			However, the UA <em>may</em> visually collapse
+			However, in order to match platform conventions for editable text fields,
+			the UA <em>may</em> visually collapse
 			the advance widths of preserved white space
-			that occur at the end of a line.
-
-			If 'text-wrap' is ''text-wrap/normal'' or ''text-wrap/balance'',
-			whether or not there are soft wrap opportunities
-			in preserved sequences of white space,
-			and if yes where and under what condition,
-			is UA defined.
-
-			Both with regards to collapsing
-			and to soft wrap opportunities,
-			the UA should follow platform conventions.
+			that occurs at the end of a line,
+			and is not required to honor soft wrap opportunities between such spaces.
 
 		<dt><dfn>preserve-trim</dfn>
 		<dd>
@@ -94,7 +86,9 @@ White Space Collapsing: the 'text-space-collapse' property</h3>
 
 			Issue: The CSSWG would appreciate feedback
 			on the use cases for this value,
-			to evaluate whether trimming leading spaces
+			to evaluate whether
+			this value is needed at all
+			and if so, if trimming leading spaces
 			could be needed as well.
 
 		<dt><dfn>preserve-breaks</dfn>