Perform the immediate block inlining more often.

Previously, dynamic compilation meant we didn't do it as we might
mess up closures taking at BEGIN time. However, that was overly
pessimistic. We can in fact perform the optimization provided no
possible closures exist to have been taken at BEGIN time. Improves
quality of code in CORE.setting a good bit, knocking 4 GC runs and
2.5% of the runtime off Text::CSV, for example.

src/Perl6/Optimizer.nqp

@@ -927,8 +927,7 @@ class Perl6::Optimizer {
         my int $flattened := 0;
         my $result        := $block;
         if $block.blocktype eq 'immediate' && $block.arity == 0
-                && !$*DYNAMICALLY_COMPILED && !$vars_info.is_poisoned
-                && !$block.has_exit_handler {
+                && !$vars_info.is_poisoned && !$block.has_exit_handler {
             # Scan symbols for any non-interesting ones.
             my @sigsyms;
             for $block.symtable() {
@@ -937,6 +936,16 @@ class Perl6::Optimizer {
                     @sigsyms.push($name);
                 }
             }
+
+            # If we dynamically compiled it, then it must not contain
+            # any nested blocks.
+            if $*DYNAMICALLY_COMPILED {
+                for $block[0].list {
+                    if nqp::istype($_, QAST::Block) && $_.blocktype ne 'raw' {
+                        @sigsyms.push('');
+                    }
+                }
+            }
 
             # If we have no interesting ones, then we can inline the
             # statements.