RFR: 8299807: newStringNoRepl should avoid copying arrays for ASCII compatible charsets [v2]

[Glavo]

> This is the javadoc of `JavaLangAccess::newStringNoRepl`:
> 
> 
>     /**
>      * Constructs a new {@code String} by decoding the specified subarray of
>      * bytes using the specified {@linkplain java.nio.charset.Charset charset}.
>      *
>      * The caller of this method shall relinquish and transfer the ownership of
>      * the byte array to the callee since the later will not make a copy.
>      *
>      * @param bytes the byte array source
>      * @param cs the Charset
>      * @return the newly created string
>      * @throws CharacterCodingException for malformed or unmappable bytes
>      */
> 
> 
> It is recorded in the document that it should be able to directly construct strings with parameter byte array to reduce array allocation.
> 
> However, at present, `newStringNoRepl` always copies arrays for UTF-8 or other ASCII compatible charsets.
> 
> This PR fixes this problem.

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

  update

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/12119/files
  - new: https://git.openjdk.org/jdk/pull/12119/files/9ec85ef0..5a0feb8b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12119&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12119&range=00-01

  Stats: 10 lines in 2 files changed: 5 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/12119.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12119/head:pull/12119

PR: https://git.openjdk.org/jdk/pull/12119