This PR is a fix for [JDK-8232824](https://bugs.openjdk.java.net/browse/JDK-8232824) This issue is regression of [JDK-8187074](https://bugs.openjdk.java.net/browse/JDK-8187074).
Issue. - `Parent.viewOrderChildren` is a list of children sorted according to view order. - `Parent.viewOrderChildren` is cleared and computed in `Parent.computeViewOrderChildren()` which is called from `Parent.doUpdatePeer()` when a `pulse `is received. - Below is the scenario mentioned in this issue, 1. `TabPane` is created with few `tabs`. 2. For each tab, a `TabHeaderSkin` is created with `setViewOrder(1)` and is added to `TabHeaderArea.headersRegion` 3. All these `TabHeaderSkin`s are added to `Parent.viewOrderChildren` on `pulse`. 4. When the `TabPane` is removed from scene, then on the next pulse the method `Parent.doUpdatePeer()` does not get called for `TabHeaderArea.headersRegion`, because it is not part for scenegraph anymore. So `Parent.computeViewOrderChildren()` does not get called and the `Parent.viewOrderChildren` does not get cleared, which causes the leak. Fix: Clear the `Parent.viewOrderChildren` list when marking `DirtyBits.PARENT_CHILDREN_VIEW_ORDER` as dirty. `Parent.viewOrderChildren` will be computed on next `pulse`. This will maintain lazy computation of `Parent.viewOrderChildren`. Added a system test, fails without fix and passes with. No failures in existing tests. ------------- Commits: - cbcc3161: [WIP] 8232824: Removing TabPane with strong referenced content causes memory leak from weak one Changes: https://git.openjdk.java.net/jfx/pull/79/files Webrev: https://webrevs.openjdk.java.net/jfx/79/webrev.00 Issue: https://bugs.openjdk.java.net/browse/JDK-8232824 Stats: 120 lines in 2 files changed: 118 ins; 0 del; 2 mod Patch: https://git.openjdk.java.net/jfx/pull/79.diff Fetch: git fetch https://git.openjdk.java.net/jfx pull/79/head:pull/79 PR: https://git.openjdk.java.net/jfx/pull/79
