[lworld][c1] Block merging need to preserve type info for flattened arrays

For the following bytecodes:

       0: iload_0
       1: ifeq 12
       4: iconst_5
       5: anewarray #2 // class "QV;"
       8: astore_1
       9: goto 18
      12: bipush 10
      14: anewarray #2 // class "QV;"
      17: astore_1
>> 18: aload_1
      19: iconst_0
      20: aaload

At bytecode 18, the type of local #1 is merged. BlockBegin::try_merge() would just tag it as an object, losing the exact type information, which should be "[QV;".

Because the aaload bytecode at 20 doesn't carry type information, it has no idea whether it suppose to access a flattened array.

Only aaload/asstore seem to be affected. For example, getfield carry type information so it knows whether it's accessing a flattened field or not.