Change textarea's relevant value to its API value

Per the test case included as an example in the spec, this is more in
line with browser behavior, and makes more sense. A similar conclusion
was reached on related matters in
whatwg#2424, and also in
whatwg#2437.

Author: domenic

source

@@ -54726,10 +54726,30 @@ MIT Room 32-G524
 
   <p>For <code>input</code> elements, these APIs must operate on the element's <span
   data-x="concept-fe-value">value</span>. For <code>textarea</code> elements, these APIs must
-  operate on the element's <span data-x="concept-textarea-raw-value">raw value</span>. In the below
+  operate on the element's <span data-x="concept-fe-api-value">API value</span>. In the below
   algorithms, we call the value string being operated on the <dfn
   data-x="concept-textarea/input-relevant-value">relevant value</dfn>.</p>
 
+  <div class="example">
+   <p>The use of <span data-x="concept-fe-api-value">API value</span> instead of <span
+   data-x="concept-textarea-raw-value">raw value</span> for <code>textarea</code> elements means
+   that U+000D (CR) characters are normalized away. For example,
+
+   <pre>&lt;textarea id="demo">&lt;/textarea>
+&lt;script>
+ demo.value = "A\r\nB";
+ demo.setRangeText("replaced", 0, 2);
+ assert(demo.value === "replacedB");
+&lt;/script></pre>
+
+   <p>If we had operated on the <span data-x="concept-textarea-raw-value">raw value</span> of "<code
+   data-x="">A\r\nB</code>", then we would have replaced the characters "<code
+   data-x="">A\r</code>", ending up with a result of "<code data-x="">replaced\nB</code>". But since
+   we used the <span data-x="concept-fe-api-value">API value</span> of "<code
+   data-x="">A\nB</code>", we replaced the characters "<code data-x="">A\n</code>", giving "<code
+   data-x="">replacedB</code>".</p>
+  </div>
+
   <p>Characters with no visible rendering, such as U+200D ZERO WIDTH JOINER, still count as
   characters. Thus, for instance, the selection can include just an invisible character, and the
   text insertion cursor can be placed to one side or another of such a character.</p>