After [JDK-8157900](https://bugs.openjdk.java.net/browse/JDK-8157900), initializeThickness() moved from ScrollBarThemeImpl to ScrollBarWidget but the implementation was kept the same by using testSBRef to call setThickness() for setting ScrollBarTheme.thickness.
Modifying initializeThickness() to set ScrollBarTheme.thickness once and removing testSBRef. ------------- Commit messages: - 8171898: [WebView] ScrollBarWidget thickness calculation is not correct Changes: https://git.openjdk.java.net/jfx/pull/197/files Webrev: https://webrevs.openjdk.java.net/jfx/197/webrev.00 Issue: https://bugs.openjdk.java.net/browse/JDK-8171898 Stats: 22 lines in 2 files changed: 0 ins; 15 del; 7 mod Patch: https://git.openjdk.java.net/jfx/pull/197.diff Fetch: git fetch https://git.openjdk.java.net/jfx pull/197/head:pull/197 PR: https://git.openjdk.java.net/jfx/pull/197
