Don't emit inner classes as static classes

`isOriginallyStaticOwner` did the wrong thing and return true for pretty
much any class (because after LambdaLift, all classes are top-level, so
they're always static), this had no effect on Scala code but prevented
Java code from instantiating these classes.

The new implementation is identical to the one used in scalac and
matches the documentation comment for the method.

This allows t10889 from scala/scala#7975 to
pass.

Author: smarter

compiler/src/dotty/tools/backend/jvm/BackendInterface.scala

@@ -583,8 +583,8 @@ abstract class BackendInterface extends BackendInterfaceDefinitions {
      *   object T { def f { object U } }
      * the owner of U is T, so UModuleClass.isStatic is true. Phase travel does not help here.
      */
-    def isOriginallyStaticOwner: Boolean
-
+    def isOriginallyStaticOwner: Boolean =
+      isPackageClass || isModuleClass && originalOwner.isOriginallyStaticOwner
 
     def samMethod(): Symbol
 

compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala

@@ -839,18 +839,6 @@ class DottyBackendInterface(outputDirectory: AbstractFile, val superCallsMap: Ma
         toDenot(sym).owner.is(Flags.PackageClass)
       }
 
-    /**
-     * This is basically a re-implementation of sym.isStaticOwner, but using the originalOwner chain.
-     *
-     * The problem is that we are interested in a source-level property. Various phases changed the
-     * symbol's properties in the meantime, mostly lambdalift modified (destructively) the owner.
-     * Therefore, `sym.isStatic` is not what we want. For example, in
-     *   object T { def f { object U } }
-     * the owner of U is T, so UModuleClass.isStatic is true. Phase travel does not help here.
-     */
-    def isOriginallyStaticOwner: Boolean = sym.isStatic
-
-
     def addRemoteRemoteExceptionAnnotation: Unit = ()
 
     def samMethod(): Symbol =

compiler/test/dotc/run-test-pickling.blacklist

@@ -15,3 +15,4 @@ instances.scala
 instances-anonymous.scala
 mixin-forwarder-overload
 t8905
+t10889

tests/run/t10889.check

@@ -0,0 +1 @@
+new O(o).I[](i)

tests/run/t10889/O.scala

@@ -0,0 +1,6 @@
+package p
+class O(val o: String) {
+  class I[T](val i: String) {
+    println(s"new O($o).I[]($i)")
+  }
+}

tests/run/t10889/Test.java

@@ -0,0 +1,6 @@
+public class Test {
+  public static void main(String[] args) {
+    p.O l = new p.O("o");
+    p.O.I<Object> s = l.new I<Object>(/*l,*/ "i");
+  }
+}