add: Runtime.LoadScript

[shargon]

Require neo-project/neo#2756

[ProDog]

Add a return value?

[shargon]

@erikzhang the unique weird thing is that, the current instruction was null after the dynamic script

    op:[019D] INITSLOT
    op:[01A0] PUSHDATA1
    op:[01A3] CONVERT
    op:[01A5] CONVERT
    op:[01A7] STLOC0
    op:[01A8] LDARG1
    op:[01A9] LDARG0
    op:[01AA] PUSH2
    op:[01AB] PACK
    op:[01AC] PUSH15
    op:[01AD] LDLOC0
    op:[01AE] SYSCALL
    op:[0000] ADD
+    op:[0001]
    op: [01B3] JMP
    op:[01B5] RET

[Ashuaidehao]

After execute "ADD", the current instruction point will auto jump to "Next" point even it is an outrange point. (see here)

 internal bool MoveNext()
        {
            Instruction? current = CurrentInstruction;
            if (current is null) return false;
            InstructionPointer += current.Size;
            return InstructionPointer < Script.Length;
        }

Dynamic Script length is 1, InstructionPointer +1, InstructionPointer will be 1.

In the next iteration, the out-range point will get a "null" instruction.
By the way, the vm will auto change "null" to "RET" instruction, so it won't be fault in vm(https://github.com/neo-project/neo-vm/blob/f48de7e595ade7c72be6ccd5cce0ab99708f0afd/src/Neo.VM/ExecutionEngine.cs#L1450).

[erikzhang]

Merge?

[shargon]

Merge?

It's ok for me