[jdk11u-dev] RFR: 8261205: AssertionError: Cannot add metadata to an intersection type

[Liam Miller-Cushon]

This is a backport of [JDK-8888888: AssertionError: Cannot add metadata to an intersection type](https://bugs.openjdk.java.net/browse/JDK-8261205)

Original patch does not apply cleanly to 11u

* I resolved a conflicted where the loop in `JavacParser` that sets `declaredUsingVar = true;` was modified by JDK-8210742
* I adjusted the changes to imports, the original patch removed an import of `com.sun.tools.javac.code.Attribute.Array` from `TypeAnnotations.java` that was still being used in 11
* I removed the use of multi-line string literals in the test
 
Testing: x86_64 build, affected tests

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Commit messages:
 - Backport 81f39ed3e0176b75dee1c8db24041545bcc68a86

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/794/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=794&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8261205
  Stats: 168 lines in 5 files changed: 163 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/794.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/794/head:pull/794

PR: https://git.openjdk.java.net/jdk11u-dev/pull/794