RFR: 8246454: Lanai: Create RenderPerf tests for rectangular and shape clips

[Alexey Ushakov]

Created the following tests:
  testClipFlatBubbles
  testClipFlatBubblesAA
  testClipFlatBoxBubbles
  testClipFlatBoxBubblesAA

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Commit messages:
 - 8246454: Lanai: Create RenderPerf tests for rectangular and shape clips

Changes: https://git.openjdk.java.net/lanai/pull/54/files
 Webrev: https://webrevs.openjdk.java.net/lanai/54/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8246454
  Stats: 51 lines in 1 file changed: 51 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/lanai/pull/54.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/54/head:pull/54

PR: https://git.openjdk.java.net/lanai/pull/54