improve side effect detection for tagged templates

Author: tsnobip

jscomp/core/js_analyzer.ml

@@ -103,7 +103,8 @@ let rec no_side_effect_expression_desc (x : J.expression_desc) =
   | String_append (a, b) | Seq (a, b) -> no_side_effect a && no_side_effect b
   | Length (e, _) | Caml_block_tag (e, _) | Typeof e -> no_side_effect e
   | Bin (op, a, b) -> op <> Eq && no_side_effect a && no_side_effect b
-  | Tagged_template (_call_expr, _strings, values) -> Ext_list.for_all values no_side_effect
+  | Tagged_template (call_expr, strings, values) -> no_side_effect call_expr &&
+      Ext_list.for_all strings no_side_effect && Ext_list.for_all values no_side_effect
   | Js_not _ | Cond _ | FlatCall _ | Call _ | New _ | Raw_js_code _
   (* actually true? *) ->
       false