Integrated: 8252949: Shape clip should use identity transform for drawing clip spans

[Ajit Ghaisas]

Issue : https://bugs.openjdk.java.net/browse/JDK-8252949
Fix :  Metal does not have glPushMatrix and glPopMatrix equivalent APIs. Hence, the transformation matrix is saved and
restored using a temporary MTLTransform object for shape clip drawing.

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Commit messages:
 - 8252949_fix

Changes: https://git.openjdk.java.net/lanai/pull/91/files
 Webrev: https://webrevs.openjdk.java.net/?repo=lanai&pr=91&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8252949
  Stats: 14 lines in 1 file changed: 14 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/lanai/pull/91.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/91/head:pull/91

PR: https://git.openjdk.java.net/lanai/pull/91