Drop no universal in deep capture set test everywhere from source 3.5

Author: odersky

compiler/src/dotty/tools/dotc/cc/CheckCaptures.scala

@@ -170,7 +170,7 @@ object CheckCaptures:
             traverse(parent)
           case t =>
             traverseChildren(t)
-    check.traverse(tp)
+    if ccConfig.allowUniversalInBoxed then check.traverse(tp)
   end disallowRootCapabilitiesIn
 
   /** Attachment key for bodies of closures, provided they are values */

tests/neg-custom-args/captures/filevar.scala

@@ -5,7 +5,7 @@ class File:
   def write(x: String): Unit = ???
 
 class Service:
-  var file: File^ = uninitialized  // error
+  var file: File^ = uninitialized  // OK, was error under sealed
   def log = file.write("log") // error, was OK under sealed
 
 def withFile[T](op: (l: caps.Capability) ?-> (f: File^{l}) => T): T =

tests/neg-custom-args/captures/outer-var.check

@@ -22,29 +22,9 @@
 13 |    y = (q: Proc)   // error
    |         ^^^^^^^
    |         Found:    Proc
-   |         Required: box () ->{p} Unit
+   |         Required: box () => Unit
    |
-   |         Note that the universal capability `cap`
-   |         cannot be included in capture set {p} of variable y
-   |
-   | longer explanation available when compiling with `-explain`
--- [E007] Type Mismatch Error: tests/neg-custom-args/captures/outer-var.scala:14:8 -------------------------------------
-14 |    y = q           // error
-   |        ^
-   |        Found:    box () ->{q} Unit
-   |        Required: box () ->{p} Unit
-   |
-   |        Note that reference (q : Proc), defined in method inner
-   |        cannot be included in outer capture set {p} of variable y
-   |
-   | longer explanation available when compiling with `-explain`
--- [E007] Type Mismatch Error: tests/neg-custom-args/captures/outer-var.scala:16:65 ------------------------------------
-16 |  var finalizeActions = collection.mutable.ListBuffer[() => Unit]() // error
-   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |                        Found:    scala.collection.mutable.ListBuffer[box () => Unit]
-   |                        Required: box scala.collection.mutable.ListBuffer[box () ->? Unit]^?
-   |
-   |                        Note that the universal capability `cap`
-   |                        cannot be included in capture set ? of variable finalizeActions
+   |         Note that () => Unit cannot be box-converted to box () => Unit
+   |         since at least one of their capture sets contains the root capability `cap`
    |
    | longer explanation available when compiling with `-explain`

tests/neg-custom-args/captures/outer-var.scala

@@ -11,8 +11,8 @@ def test(p: Proc, q: () => Unit) =
     x = q           // error
     x = (q: Proc)   // error
     y = (q: Proc)   // error
-    y = q           // error
+    y = q           // OK, was error under sealed
 
-  var finalizeActions = collection.mutable.ListBuffer[() => Unit]() // error
+  var finalizeActions = collection.mutable.ListBuffer[() => Unit]() // OK, was error under sealed