RFR: 8251464: make Node::dump(int depth) support indent [v3]

[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 with a new target base due to a merge or a rebase. The pull request now contains
one commit:

  8251464: make Node::dump(int depth) support indent

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Changes: https://git.openjdk.java.net/jdk/pull/371/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=371&range=02
  Stats: 49 lines in 5 files changed: 26 ins; 0 del; 23 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