RFR: 8281631: HashMap copy constructor and putAll can over-allocate table [v21]

[XenoAmess]

> 8281631: HashMap copy constructor and putAll can over-allocate table

XenoAmess has updated the pull request incrementally with three additional commits since the last revision:

 - refine test
 - 1. optimize IdentityHashMap that when calling ::new(Map), do not call map.size() twice but once.
   2. delete the this((int) ((1 + m.size()) * 1.1)); as it makes the table over-allocate when size = 19.
 - refine test

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7431/files
  - new: https://git.openjdk.java.net/jdk/pull/7431/files/182c22d7..6d0ab0ef

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7431&range=20
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7431&range=19-20

  Stats: 55 lines in 2 files changed: 37 ins; 3 del; 15 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7431.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7431/head:pull/7431

PR: https://git.openjdk.java.net/jdk/pull/7431