RFR: 8278759 : PointerEvent: buttons property set to 0 when mouse down [v4]

[Hima Bindu Meda]

> Basically, buttons property is a mask which represents the button/buttons clicked on the mouse.
>     It is observed that event.buttons property is set to 0 when there is mouse press or drag event.This behaviour is observed only with javafx webView.Other browsers set the buttons property to 1, when there is mouse press or drag.
>      The issue happens because the buttons property is not updated in the framework.
>      Added implementation to update and propagate the buttons property from javafx platform to native webkit.Added a robot test case for the same.
>    Performed sanity testing with the added implementation and the buttons property is compliant with the specification mentioned in https://w3c.github.io/pointerevents/#the-buttons-property.

Hima Bindu Meda has updated the pull request incrementally with one additional commit since the last revision:

  add stage show event listener

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/742/files
  - new: https://git.openjdk.java.net/jfx/pull/742/files/84b7184f..b3f4d9a8

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=742&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=742&range=02-03

  Stats: 4 lines in 1 file changed: 1 ins; 2 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/742.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/742/head:pull/742

PR: https://git.openjdk.java.net/jfx/pull/742