RFR: 8266625: The method DiagnosticSource#findLine returns wrong results when using the boundary values [v2]

[Guoxiong Li]

> Hi all,
> 
> Currently, when the file object has N characters, the method `DiagnosticSource#findLine(N)` returns true, which is a wrong result. Becase the position is zero-based, the max index is `N-1`.
> 
> The methods `getLineNumber`, `getColumnNumber` and `getLine`, which use `findLine` internally, would also return wrong results when using the boundary values.
> 
> This patch mainly fixes `DiagnosticSource#findLine(N)` by using the following code.
> 
> 
> -            return bp <= bufLen;
> +            return bp < bufLen;
> 
> 
> A corresponding test `DiagnosticSourceTest.java` is added. Then, the usages of  `getLineNumber`, `getColumnNumber` and `getLine` need to revised. And two existing tests need to be adjusted.
> 
> Thank you for taking the time to review.
> 
> Best Regards,
> --- Guoxiong

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

  Optimize test case: DiagnosticSourceTest

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3899/files
  - new: https://git.openjdk.java.net/jdk/pull/3899/files/facc5a28..a373f68a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3899&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3899&range=00-01

  Stats: 37 lines in 1 file changed: 1 ins; 17 del; 19 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3899.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3899/head:pull/3899

PR: https://git.openjdk.java.net/jdk/pull/3899