8016018: Typo in AbstractStringBuilder#indexOf and #lastIndexOf descriptions

Reviewed-by: alanb, chegar

src/share/classes/java/lang/AbstractStringBuilder.java

@@ -1307,7 +1307,7 @@ abstract class AbstractStringBuilder implements Appendable, CharSequence {
      * specified substring, starting at the specified index.  The integer
      * returned is the smallest value {@code k} for which:
      * <blockquote><pre>
-     *     k >= Math.min(fromIndex, str.length()) &&
+     *     k >= Math.min(fromIndex, this.length()) &&
      *                   this.toString().startsWith(str, k)
      * </pre></blockquote>
      * If no such value of <i>k</i> exists, then -1 is returned.
@@ -1346,7 +1346,7 @@ abstract class AbstractStringBuilder implements Appendable, CharSequence {
      * specified substring. The integer returned is the largest value <i>k</i>
      * such that:
      * <blockquote><pre>
-     *     k <= Math.min(fromIndex, str.length()) &&
+     *     k <= Math.min(fromIndex, this.length()) &&
      *                   this.toString().startsWith(str, k)
      * </pre></blockquote>
      * If no such value of <i>k</i> exists, then -1 is returned.