RFR: 8319925: CSS.BackgroundImage incorrectly uses double-checked locking [v3]

[Prasanta Sadhukhan]

> CSS.BackgroundImage.getImage uses double-checked locking but the loadedImage field isn't declared as volatile. Without the volatile modifier, double-checked locking implementation is broken.

Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:

  Set loadedImage after image load

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16917/files
  - new: https://git.openjdk.org/jdk/pull/16917/files/af2b9303..503cc2cd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16917&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16917&range=01-02

  Stats: 5 lines in 1 file changed: 2 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/16917.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16917/head:pull/16917

PR: https://git.openjdk.org/jdk/pull/16917