Fixed bigint generation on node < 10

Author: sanex3339

escodegen.js

@@ -2348,6 +2348,11 @@
               return '/' + expr.regex.pattern + '/' + expr.regex.flags;
             }
 
+            // BigInt, eg: 1n
+            if (typeof expr.bigint === 'string' && expr.raw) {
+                return expr.raw;
+            }
+
             if (expr.value === null) {
                 return 'null';
             }
@@ -2356,11 +2361,6 @@
                 return escapeString(expr.value);
             }
 
-            // BigInt, eg: 1n
-            if (typeof expr.bigint === 'string' && expr.raw) {
-                return expr.raw;
-            }
-
             if (typeof expr.value === 'number') {
                 // Has Numeric Separator
                 if (expr.raw && expr.raw.indexOf('_') !== -1) {