Fixed RegExp literal in mozilla AST generation/output and added a --dump-spidermonkey-ast flag

lib/mozilla-ast.js

@@ -146,7 +146,7 @@
               case "boolean":
                 return new (val ? AST_True : AST_False)(args);
               default:
-                args.value = val;
+                args.value = M.regex && M.raw ? M.raw : val;
                 return new AST_RegExp(args);
             }
         },
@@ -334,6 +334,19 @@
         };
     });
 
+    def_to_moz(AST_RegExp, function To_Moz_Literal(M) {
+        var value = M.value;
+        return {
+            type: "Literal",
+            value: value,
+            raw: value.toString(),
+            regex: {
+                pattern: value.source,
+                flags: value.toString().match(/[gimuy]*$/)[0]
+            }
+        };
+    });
+
     def_to_moz(AST_Constant, function To_Moz_Literal(M) {
         var value = M.value;
         if (typeof value === 'number' && (value < 0 || (value === 0 && 1 / value < 0))) {