[OpenJDK 2D-Dev] RFR: 6206189: Graphics2D.clip specifies incorrectly that a 'null' is a valid value for this method

[Prasanta Sadhukhan]

The API doc for Graphics2D.clip(shape s) claims that passing a null argument would actually clear the existing clipping area, which is incorrect.
This statement is applicable only to G2D.setClip() and not for the clip() method. G2D.clip() would throw a NullPointerException when it encounters a null argument. 
Updated spec to rectify this.

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Commit messages:
 - 6206189: Graphics2D.clip specifies incorrectly that a 'null' is a valid value for this method

Changes: https://git.openjdk.java.net/jdk/pull/2476/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2476&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-6206189
  Stats: 50 lines in 2 files changed: 48 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2476.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2476/head:pull/2476

PR: https://git.openjdk.java.net/jdk/pull/2476