RFR: 8346887: DrawFocusRect() may cause an assertion failure

[Dmitry Markov]

On Windows debug build execution of `DrawFocusRect()` may cause an assertion failure. In particular if a component, which is going to gain a focus, has zero size, the function returns `0` because focus rectangle is empty.

It is necessary to check that the focus rectangle is not empty before `DrawFocusRect()` call.

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Commit messages:
 - 8346887: DrawFocusRect() may cause an assertion failure

Changes: https://git.openjdk.org/jdk/pull/22973/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22973&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8346887
  Stats: 7 lines in 3 files changed: 0 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/22973.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22973/head:pull/22973

PR: https://git.openjdk.org/jdk/pull/22973