RFR: 8251464: make Node::dump(int depth) support indent [v2]

[Xin Liu]

> Node::dump(depth) indents 2 whitespaces for each level.
> The function isnot on until the depth of the ideal graph isnot greater
> than PrintIdealIndentThreshold (0 by default).

Xin Liu has updated the pull request incrementally with one additional commit since the last revision:

  add self-verification workflow.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/371/files
  - new: https://git.openjdk.java.net/jdk/pull/371/files/2c5376f0..af23f175

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=371&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=371&range=00-01

  Stats: 861 lines in 1 file changed: 861 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/371.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/371/head:pull/371

PR: https://git.openjdk.java.net/jdk/pull/371