hg: jdk/sandbox: 8240137: Support chained use of Content.add

[chris.hegarty at oracle.com]

Changeset: 7af6364e1792
Author:    jjg
Date:      2020-03-06 18:03 -0800
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/7af6364e1792

8240137: Support chained use of Content.add
Reviewed-by: hannesw

! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/HtmlDocletWriter.java
! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/Comment.java
! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/ContentBuilder.java
! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/Entity.java
! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/FixedStringContent.java
! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/HtmlTree.java
! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/RawHtml.java
! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/Script.java
! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/StringContent.java
! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/Table.java
! src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/toolkit/Content.java