RFR: 8275345: RasterFormatException when drawing a tiled image made of non-writable rasters [v3]

[Martin Desruisseaux]

> This commit fixes a `RasterFormatException` thrown when `Graphics2D.drawRenderedImage(…)` is invoked with an image containing tiles that are instances of `Raster` but not `WritableRaster`.
> 
> https://bugs.openjdk.java.net/browse/JDK-8275345

Martin Desruisseaux has updated the pull request incrementally with one additional commit since the last revision:

  Make the test class public for allowing execution by jtreg.
  Fix a compiler warning about raw type.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7337/files
  - new: https://git.openjdk.java.net/jdk/pull/7337/files/fea2f9c0..8b4e6f57

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7337&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7337&range=01-02

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7337.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7337/head:pull/7337

PR: https://git.openjdk.java.net/jdk/pull/7337