RFR: 8268720: Unspecified checks on NameAndType constants should not be performed

[Harold Seigel]

Please review this small fix for JDK-8268720.  The fix changes the JVM to no longer throw a ClassFormatError exception for a constant pool NameAndType that has a name and descriptor that are both valid, but are incompatible together, such as "<init>()D".

Note that if the CONSTANT_NameAndType_info for a CONSTANT_Methodref_info contained the name "<init>"and descriptor such as "()D" then a ClassFormatError exception would get thrown because the CONSTANT_Methodref_info would be invalid. JVM Spec section 4.4.2 says:

If the name of the method in a CONSTANT_Methodref_info structure begins with a '<' ('\u003c'), then the name must be the special name <init>, representing an instance initialization method (§2.9.1). The return type of such a method must be void.

The fix was tested with Mach5 tiers 1 and 2 on Linux, Mac OS, and Windows, Mach5 tiers 3-5 on Linux x64, and JCK Lang and VM tests on Linux x64.

Thanks, Harold

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Commit messages:
 - 8268720: Unspecified checks on NameAndType constants should not be performed

Changes: https://git.openjdk.java.net/jdk/pull/4497/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4497&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268720
  Stats: 309 lines in 3 files changed: 300 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4497.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4497/head:pull/4497

PR: https://git.openjdk.java.net/jdk/pull/4497