asm: Frame: increase DIM_SIZE to support high dimension arrays
An array type is valid with 255 or fewer dimensions, said by the jvms. IMO, ClassWriter
should support such merged type.
The remaining 18 bits are still enough to contain the corresponding type due to the bytecode length limit.
It should be OK to call method String.repeat(int)
which is availiable since java 11 from the test code.