Fix AST-gen for blocks in hash constructors.

Need to migrate inner blocks out to the right scope, given that the
hash constructor does not imply one. Fixes "on" with the EnumMap
case on MoarVM, and no doubt some other things.

src/Perl6/Actions.nqp

@@ -4683,6 +4683,7 @@ class Perl6::Actions is HLL::Actions does STDActions {
             }
         }
         if $is_hash && $past<past_block>.arity == 0 {
+            migrate_blocks($past<past_block>, $*W.cur_lexpad());
             my @children := @($past<past_block>[1]);
             $past := QAST::Op.new(
                 :op('call'),
@@ -4715,6 +4716,28 @@ class Perl6::Actions is HLL::Actions does STDActions {
         make $past;
     }
 
+    # Some constructs are parsed and compiled with blocks inside of them, but
+    # then the outer block goes away (for example, when a {...} becomes a
+    # hash). This is used to move blocks out of the discarded inner one to
+    # the outer one, so they're correctly lexically scoped.
+    sub migrate_blocks($from, $to) {
+        my @decls := @($from[0]);
+        my int $n := nqp::elems(@decls);
+        my int $i := 0;
+        while $i < $n {
+            if nqp::istype(@decls[$i], QAST::Block) {
+                $to[0].push(@decls[$i]);
+                @decls[$i] := QAST::Op.new( :op('null') );
+            }
+            elsif nqp::istype(@decls[$i], QAST::Stmt) &&
+                  nqp::istype(@decls[$i][0], QAST::Block) {
+                $to[0].push(@decls[$i][0]);
+                @decls[$i][0] := QAST::Op.new( :op('null') );
+            }
+            $i++;
+        }
+    }
+
     method circumfix:sym<[ ]>($/) {
         make QAST::Op.new( :op('call'), :name('&circumfix:<[ ]>'), $<semilist>.ast, :node($/) );
     }