consider some `__js__` calls to be harmless

analyzer.ml

@@ -899,6 +899,11 @@ module TexprTransformer = struct
 			close_node g bb;
 			g.g_unreachable
 		in
+		let r = Str.regexp "^\\([A-Za-z0-9_]\\)+$" in
+		let check_unbound_call v el = match v.v_name,el with
+			| "__js__",[{eexpr = TConst (TString s)}] when Str.string_match r s 0 -> ()
+			| _ -> ctx.has_unbound <- true
+		in
 		let rec value bb e = match e.eexpr with
 			| TLocal v ->
 				bb,e
@@ -910,8 +915,8 @@ module TexprTransformer = struct
 				bind_to_temp bb false e
 			| TFor _ | TWhile _ ->
 				assert false
-			| TCall({eexpr = TLocal v},_) when is_unbound v ->
-				ctx.has_unbound <- true;
+			| TCall({eexpr = TLocal v},el) when is_unbound v ->
+				check_unbound_call v el;
 				bb,e
 			| TCall(e1,el) ->
 				call bb e e1 el
@@ -1264,8 +1269,8 @@ module TexprTransformer = struct
 					add_terminator bb {e with eexpr = TThrow e1};
 				end
 			(* side_effects *)
-			| TCall({eexpr = TLocal v},_) when is_unbound v ->
-				ctx.has_unbound <- true;
+			| TCall({eexpr = TLocal v},el) when is_unbound v ->
+				check_unbound_call v el;
 				add_texpr g bb e;
 				bb
 			| TCall(e1,el) ->

tests/optimization/src/TestJs.hx

@@ -231,14 +231,12 @@ class TestJs {
 	@:js('
 		var map = new haxe_ds_StringMap();
 		if(__map_reserved.some != null) map.setReserved("some",2); else map.h["some"] = 2;
-		var i = 2;
-		TestJs["use"](i);
+		TestJs["use"](2);
 	')
 	static function testIssue4731() {
         var map = new Map();
         var i = map["some"] = 2;
 		use(i);
-		// This is not const-propagated because StringMap introduced unbound variables
 	}
 
 	@:js('