RFR: 8206253: No/Wrong scroll events from touch input in window mode

[Jose Pereda]

This PR changes the parameter names to accommodate class calculations related to screen event coordinates (AbsX, AbsY).

As [discussed](https://bugs.openjdk.java.net/browse/JDK-8206253?focusedCommentId=14405707&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14405707), the sendScrollXXXEvent methods are currently passing the screen coordinates (AbsX, AbsY) to the local ones, but they shouldn't modify those, but the screen ones.

Tested successfully on Android with ComboBox controls in different positions.

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Commit messages:
 - Change parameter names to accommodate class calculations

Changes: https://git.openjdk.java.net/jfx/pull/420/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=420&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8206253
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jfx/pull/420.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/420/head:pull/420

PR: https://git.openjdk.java.net/jfx/pull/420