RFR: 8375225: WebIObserverTest fails with WebKit 623.1

[Jay Bhaskar]

Issue: WebIObserverTest fails with WebKit 623.1 due to float value comparison
Solution: Adjusting the test because WebKit rect calculations moved to floating-point, so the intersection ratio is no longer an exact value.

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Commit messages:
 - add delta for IntersectionRatio as All rect width height calculation is now in Float

Changes: https://git.openjdk.org/jfx/pull/2049/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=2049&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8375225
  Stats: 4 lines in 1 file changed: 2 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jfx/pull/2049.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/2049/head:pull/2049

PR: https://git.openjdk.org/jfx/pull/2049