Integrated: 8252371: LCD text rendered with Metal pipeline is corrupted

[Jayathirth D V]

Implemented code to use correct texture coordinates to read destination color.

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Commit messages:
 - 8252371: LCD text rendered with Metal pipeline is corrupted

Changes: https://git.openjdk.java.net/lanai/pull/81/files
 Webrev: https://webrevs.openjdk.java.net/lanai/81/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8252371
  Stats: 38 lines in 2 files changed: 30 ins; 1 del; 7 mod
  Patch: https://git.openjdk.java.net/lanai/pull/81.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/81/head:pull/81

PR: https://git.openjdk.java.net/lanai/pull/81