hg: jdk/client: 8242557: Add length limit for strings in PNGImageWriter

[jayathirth.d.v at oracle.com]

Changeset: 645c71334acd
Author:    jdv
Date:      2020-04-30 20:03 +0530
URL:       https://hg.openjdk.java.net/jdk/client/rev/645c71334acd

8242557: Add length limit for strings in PNGImageWriter
Reviewed-by: prr, psadhukhan

! src/java.desktop/share/classes/com/sun/imageio/plugins/png/PNGImageWriter.java
+ test/jdk/javax/imageio/plugins/png/WriteInvalidKeywordTest.java