[Rev 02] RFR: 8088198: Exception thrown from snapshot if dimensions are larger than max texture size

[Frederic Thevenet]

> This PR aims to address the following issue: JDK-8088198 Exception thrown from snapshot if dimensions are larger than max texture size
> 
> In order to do that, it simply captures snapshots in multiple tiles of maxTextureSize^2 dimensions (or less, as needed), and then recomposes all the tiles into a a single image.
> Other than that, the logic used to do the actual snapshot is unchanged.
> 
> Tests using the existing SnapshotCommon class have been added in a new file named Snapshot3Test under SystemTest/test/javafx/scene.
> These tests pass with the proposed fix, and fail without, throwing " java.lang.IllegalArgumentException: Unrecognized image loader: null"

The pull request has been updated with 2 additional commits.

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Added commits:
 - 50191728: Several changes following code review
 - d4ecb734: Removed Snapshot3Test.java and re-enabled ignored tests in Snapshot2Test.java

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/68/files
  - new: https://git.openjdk.java.net/jfx/pull/68/files/9986809d..50191728

Webrevs:
 - full: https://webrevs.openjdk.java.net/jfx/68/webrev.02
 - incr: https://webrevs.openjdk.java.net/jfx/68/webrev.01-02

  Stats: 82 lines in 3 files changed: 1 ins; 71 del; 10 mod
  Patch: https://git.openjdk.java.net/jfx/pull/68.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/68/head:pull/68

PR: https://git.openjdk.java.net/jfx/pull/68