Decay Array iso references to Array ref before calling box methods.

This is a workaround for ponylang#1887

packages/buffered/_test.pony

@@ -118,7 +118,8 @@ class iso _TestWriter is UnitTest
         [as U8: '\n'; 't'; 'h'; 'e']
         [as U8: 'r'; 'e'; '\r'; '\n']] end)
 
-    for bs in wb.done().values() do
+    let wb' : Array[(String val | Array[U8 val] val)] ref = wb.done()
+    for bs in wb'.values() do
       try
         b.append(bs as Array[U8] val)
       end

packages/files/directory.pony

@@ -426,7 +426,8 @@ class Directory
         if fi.directory and not fi.symlink then
           let directory = open(target)
 
-          for entry in directory.entries().values() do
+          let dir_entries : Array[String] ref = directory.entries()
+          for entry in dir_entries.values() do
             if not directory.remove(entry) then
               return false
             end

packages/files/file_path.pony

@@ -196,7 +196,8 @@ class val FilePath
       if info.directory and not info.symlink then
         let directory = Directory(this)
 
-        for entry in directory.entries().values() do
+        let entries : Array[String] ref = directory.entries()
+        for entry in entries.values() do
           if not join(entry).remove() then
             return false
           end

packages/term/ansi_term.pony

@@ -80,7 +80,8 @@ actor ANSITerm
       return
     end
 
-    for c in (consume data).values() do
+    let data' : Array[U8] ref = consume data
+    for c in data'.values() do
       match _escape
       | _EscapeNone =>
         if c == 0x1B then