Review request for OPENJDK6-40: OpenJDK6-b32 does not compile the testcase that Oracle JDK 6u45 compiles fine

[Nikolay Gorshkov]

Please, review the fix for
OPENJDK6-40: OpenJDK6-b32 does not compile the testcase that Oracle JDK 6u45 
compiles fine

This is a regression of the fix for OPENJDK6-35 (which is a backport of
JDK-6650759 to OpenJDK 6). In OpenJDK 7 this regression existed too -
it was tracked as
JDK-6938454: Unable to determine generic type in program that compiles under Java 6
The solution is to backport the fix for JDK-6938454 to OpenJDK 6.
The backport is small and straightforward, but not identical to the original
fix - the changes related to "diamond" operator support are not applicable
to OpenJDK 6.

The practical reason for this fix is that currently OpenJDK 6 fails to compile
Apache Flume 1.5.0, while Oracle Java 6 and 7 do the compilation successfully.

Bug: https://java.net/jira/browse/OPENJDK6-40
OpenJDK bug: https://bugs.openjdk.java.net/browse/JDK-6938454
Webrev: http://cr.openjdk.java.net/~ikrylov/openjdk6bug40.langtools.webrev/

Testing: builds on Windows and Linux, all regression tests for javac, building
Apache Flume 1.5.0.

Thanks,
Nikolay