RFR: 8313709: Wrong layout of a FlowPane in a BorderPane in a ScrollPane, if padding is too big

[Jose Pereda]

So far, BorderPane does the calculation for the children min/pref width/height taken into account only the margin applied to them, if any, but not the total padding that could be applied as well to the BorderPane itself.

However, this padding needs to be taken into account as well, and this PR modifies BorderPane to subtract its insets from its size while doing the children min/pref width/height calculations.

A parameterized test has been included. 

It is a simplified version of the test case attached to https://bugs.openjdk.org/browse/JDK-8313709, but still shows how without this patch, two of the cases (padding with or without margin) fail, while pass with it.

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Commit messages:
 - modify test
 - Subtract borderPane insets from size for children min/pref calculations, including test

Changes: https://git.openjdk.org/jfx/pull/1203/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1203&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8313709
  Stats: 74 lines in 2 files changed: 67 ins; 2 del; 5 mod
  Patch: https://git.openjdk.org/jfx/pull/1203.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1203/head:pull/1203

PR: https://git.openjdk.org/jfx/pull/1203