Fix bug: evaluate value error for enum-type   for example:       typedef enum { A, B = -1, C } enum_e;     C should be 0. but C = 2 in old version.
Fix bug: evaluate value error for enum-type
  for example:
      typedef enum { A, B = -1, C } enum_e;
    C should be 0. but C = 2 in old version.

ilc-opensource/io-js,ilc-opensource/io-js,ilc-opensource/io-js,ilc-opensource/io-js,ilc-opensource/io-js