Collapse putobject, putobject, newarray

This collapses:

```
== disasm: #<ISeq:bar@bench.rb:3 (3,0)-(5,3)> (catch: FALSE)
0000 putobject                    "a"                                 (   4)[LiCa]
0002 putobject                    "b"
0004 putobject                    "c"
0006 putobject                    "d"
0008 putobject                    "e"
0010 putobject                    "f"
0012 putobject                    "g"
0014 putobject                    "h"
0016 putobject                    "i"
0018 putobject                    "j"
0020 putobject                    "k"
0022 newarray                     11
0024 leave                                                            (   5)[Re]
```

In to this:

```
== disasm: #<ISeq:bar@bench.rb:3 (3,0)-(5,3)> (catch: FALSE)
0000 duparray                     ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k"](   4)[LiCa]
0002 leave                                                            (   5)[Re]
```

Author: tenderlove

compile.c

@@ -3847,7 +3847,7 @@ enum compile_array_type_t {
 };
 
 static inline int
-static_literal_node_p(const NODE *node)
+static_literal_node_p(const NODE *node, const rb_iseq_t *iseq)
 {
     node = node->nd_head;
     switch (nd_type(node)) {
@@ -3856,6 +3856,12 @@ static_literal_node_p(const NODE *node)
       case NODE_TRUE:
       case NODE_FALSE:
 	return TRUE;
+      case NODE_STR:
+	if (ISEQ_COMPILE_DATA(iseq)->option->frozen_string_literal) {
+	    return TRUE;
+	} else {
+	    return FALSE;
+	}
       default:
 	return FALSE;
     }
@@ -3872,6 +3878,8 @@ static_literal_value(const NODE *node)
 	return Qtrue;
       case NODE_FALSE:
 	return Qfalse;
+      case NODE_STR:
+	return rb_fstring(node->nd_lit);
       default:
 	return node->nd_lit;
     }
@@ -3921,7 +3929,7 @@ compile_array(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *const node_ro
 		    }
 		    break;
 		}
-		if (opt_p && !static_literal_node_p(node)) {
+		if (opt_p && !static_literal_node_p(node, iseq)) {
 		    opt_p = 0;
 		}
 
@@ -3947,8 +3955,8 @@ compile_array(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *const node_ro
 			node = node->nd_next;
 		    }
 		    while (node && node->nd_next &&
-			   static_literal_node_p(node) &&
-			   static_literal_node_p(node->nd_next)) {
+			   static_literal_node_p(node, iseq) &&
+			   static_literal_node_p(node->nd_next, iseq)) {
 			VALUE elem[2];
 			elem[0] = static_literal_value(node);
 			elem[1] = static_literal_value(node->nd_next);

test/ruby/test_literal.rb

@@ -177,6 +177,12 @@ def test_frozen_string
     end
   end
 
+  def test_frozen_string_in_array_literal
+    list = eval("# frozen-string-literal: true\n""['foo', 'bar']")
+    assert_equal 2, list.length
+    list.each { |str| assert_predicate str, :frozen? }
+  end
+
   if defined?(RubyVM::InstructionSequence.compile_option) and
     RubyVM::InstructionSequence.compile_option.key?(:debug_frozen_string_literal)
     def test_debug_frozen_string