Fix for empty lines in squiggly heredocs

test/t/literals.rb

@@ -181,6 +181,12 @@ QQ2
   UUU2
     u#{3}u
   UUU3
+  v = <<~VVV
+
+\tvvv
+\t\t
+\t#{123}
+  VVV
 
   w = %W( 1 #{<<WWW} 3
 www
@@ -221,6 +227,7 @@ ZZZ
   assert_equal "sss\n  sss\n", s
   assert_equal "ttt\n  ttt\n", t
   assert_equal ["u1u\n", "u2u\n", "u\#{3}u\n"], u
+  assert_equal "\nvvv\n\t\n123\n", v
   assert_equal ["1", "www\n", "3", "4", "5"], w
   assert_equal [1, "foo 222 333\n 444\n5\n bar\n6\n", 9], x
   assert_equal "", z