No longer need to wrap files with contentContainer

JDK-8231144 was a changeset to work around a design issue in the generated javadoc output. At the time, it was a reasonable fix.

But, the javadoc design problem is being fixed, and when it has been fixed, the changes from JDK-8231144 will no longer be required, and can be removed, if you choose to do so. The javadoc fix ius JDK-8239817.

Note: there is no requirement to do so: the effect until you decide to remove these nodes will just be that you have a reference to a non-existent style class, which should have no effect.

Note that once the javadoc bug has been fixed, there should be no visual change in the presentation of the page, whether you leave the div elements in place or remove them.