RFR: JDK-8274781: Use monospace font for enclosing interface

[Hannes Wallnöfer]

Please review a trivial change to have the enclosing interface/class link in the class page displayed in monospace font like other similar links.

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Commit messages:
 - JDK-8274781: Use monospace font for enclosing interface

Changes: https://git.openjdk.java.net/jdk/pull/5945/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5945&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274781
  Stats: 6 lines in 3 files changed: 1 ins; 1 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5945.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5945/head:pull/5945

PR: https://git.openjdk.java.net/jdk/pull/5945