RFR: JDK-8266281: Assign Symbols to the package selector expression

[Jan Lahoda]

The proposal in this patch is that package names in the package clause would be attributed with the appropriate PackageSymbols. So when using Trees.getElement on an AST node of some part of the package name, a sensible PackageSymbol would be returned.

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Commit messages:
 - JDK-8266281: Assign Symbols to the package selector expression

Changes: https://git.openjdk.java.net/jdk/pull/3977/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3977&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8266281
  Stats: 35 lines in 5 files changed: 26 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3977.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3977/head:pull/3977

PR: https://git.openjdk.java.net/jdk/pull/3977