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"

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Commits:
 - 4bc44173: 8088198: Exception thrown from snapshot if dimensions are larger than max texture size

Changes: https://git.openjdk.java.net/jfx/pull/68/files
 Webrev: https://webrevs.openjdk.java.net/jfx/68/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8088198
  Stats: 142 lines in 2 files changed: 111 ins; 11 del; 20 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