Revert "Optimize ThreadLocalCache while perusal the code."

Reverts alibaba/fastjson#222
mvn test can not pass

  test_bytes(com.alibaba.json.bvt.JSONTest_Bytes): illegal state: minExp 10, maxExp17, length 23
  test_utf_4(com.alibaba.json.bvt.parser.TestUTF8_2): illegal state: minExp 10, maxExp17, length 20
  testBytes(com.alibaba.json.bvt.util.ThreadLocalCacheTest): illegal state: minExp 10, maxExp17, length 2048
  test(com.alibaba.json.bvt.util.ThreadLocalCacheTest): illegal state: minExp 10, maxExp17, length 2048