RFR: 8204568: Relative CSS-Attributes don't work all time [v4]

[Ambarish Rapte]

> Issue is that the size of properties that are relatively(`em`) sized is not computed correctly when the reference `-fx-font-size` is also specified relatively and is nested.
> 
> Fix is a slight variation of an earlier suggestion in [the PR](https://github.com/javafxports/openjdk-jfx/pull/94).
> 
> Fix is very specific to this scenario and did not show any side effect nor any test failure.
> 
> There are 12 new unit tests added along with fix:
> - Two tests fail before and pass after this fix. These test verify the reported failing scenario.
> sameRelativeFontSizeNestedParentTest
> relativeFontSizeDeepNestedParentControlTest
> - Two other tests fail both before and after this fix. They are not related to the fix. These two tests are ignored. I shall file new JBS issues to track these cases and update PR with the IDs added to @Ignore.
> propertySizesRelativeToFontSizeOfControlTest
> propertySizesRelativeToFontSizeOfParentTest
> - Other 8 tests are sanity tests which pass both before and after this fix.

Ambarish Rapte has updated the pull request incrementally with one additional commit since the last revision:

  rephrasing comment statements and review corrections

-------------

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/397/files
  - new: https://git.openjdk.java.net/jfx/pull/397/files/1b17d26a..ba8b4ba0

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=397&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=397&range=02-03

  Stats: 27 lines in 2 files changed: 4 ins; 1 del; 22 mod
  Patch: https://git.openjdk.java.net/jfx/pull/397.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/397/head:pull/397

PR: https://git.openjdk.java.net/jfx/pull/397