fix code

hutool-json/src/main/java/cn/hutool/json/JSONUtil.java

@@ -675,14 +675,12 @@ public class JSONUtil {
 			return writer;
 		}
 
-		char b; // 前一个字符
 		char c; // 当前字符
 		int len = str.length();
 		if (isWrap) {
 			writer.write('"');
 		}
 		for (int i = 0; i < len; i++) {
-//			b = c;
 			c = str.charAt(i);
 			switch (c) {
 				case '\\':
@@ -690,13 +688,6 @@ public class JSONUtil {
 					writer.write("\\");
 					writer.write(c);
 					break;
-					//此处转义导致输出不和预期一致
-//				case '/':
-//					if (b == '<') {
-//						writer.write('\\');
-//					}
-//					writer.write(c);
-//					break;
 				default:
 					writer.write(escape(c));
 			}