Lower the ES target for instanceof code (#3618)

Since #3053 the code makes use of the ES2019 optional catch binding syntax, while generated code in general seems to be compatible with ES2015.

Author: cschramm

crates/cli-support/src/js/mod.rs

@@ -3023,7 +3023,7 @@ impl<'a> Context<'a> {
                     let result;
                     try {{
                         result = {} instanceof {};
-                    }} catch {{
+                    }} catch (_) {{
                         result = false;
                     }}
                     ",