RFR: 8267221: jshell feedback is incorrect when creating method with array varargs parameter

[Jan Lahoda]

When writing something like `void t(int[]... p) {}` into JShell, one gets:

jshell> void t(int[]... p) {}
|  created method t(int[])


Note the wrong parameter type `int[]` instead of `int[]...` or at least `int[][]`. The reason is that the span of the type is incorrect when the type is varargs. The proposed patch is an attempt to fix the span.

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Commit messages:
 - 8267221: jshell feedback is incorrect when creating method with array varargs parameter

Changes: https://git.openjdk.java.net/jdk/pull/4187/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4187&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267221
  Stats: 34 lines in 3 files changed: 32 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4187.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4187/head:pull/4187

PR: https://git.openjdk.java.net/jdk/pull/4187