Follow up to JDK-8255856

(1) There is no need to persist the RestrictedType annotation in the class files or have them loaded at run time. Source file level retention is good enough.

(2) @RestrictedType annotating a field which was declared to be a
reference projection, results in a compilation error:

    @RestrictedType("QPoint;")
    public Point.ref p368;

$ javac PointBox.java
PointBox.java:12: error: scoping construct cannot be annotated with type-use annotation: @java.lang.invoke.RestrictedType("QPoint;")
    public Point.ref p368;

(3) Frederic reports that independent compiles trigger an assertion error in:
at jdk.compiler/com.sun.tools.javac.jvm.ClassReader$28.read(ClassReader.java:1273)
at jdk.compiler/com.sun.tools.javac.jvm.ClassReader.readAttrs(ClassReader.java:1408)
at jdk.compiler/com.sun.tools.javac.jvm.ClassReader.readMemberAttrs(ClassReader.java:1398)
at jdk.compiler/com.sun.tools.javac.jvm.ClassReader.readField(ClassReader.java:2242)
at jdk.compiler/com.sun.tools.javac.jvm.ClassReader.readClass(ClassReader.java:2595)
at jdk.compiler/com.sun.tools.javac.jvm.ClassReader.readClassBuffer(ClassReader.java:2674)
at jdk.compiler/com.sun.tools.javac.jvm.ClassReader.readClassFileInternal(ClassReader.java:2714)
at jdk.compiler/com.sun.tools.javac.jvm.ClassReader.readClassFile(ClassReader.java:2678)
at jdk.compiler/com.sun.tools.javac.code.ClassFinder.fillIn(ClassFinder.java:362)

(4) The tests are better written avoiding javacp output since this makes them fragile to constant pool index changes.