RFR: 8266014: Regression brought by optimization done with JDK-4926314 [v2]

[Brian Burkhalter]

> Please consider this request to correct a minor problem with the optimization added for JDK-4926314. The change is to attempt to read the number of elements remaining in the target buffer unless that number is non-positive in which case read zero. The test addition fails without and passes with the implementation change.

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

  8266014: Clean up spurious line break in the test

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3708/files
  - new: https://git.openjdk.java.net/jdk/pull/3708/files/198e09ce..50cb65c8

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3708&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3708&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3708.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3708/head:pull/3708

PR: https://git.openjdk.java.net/jdk/pull/3708