Currently, ADL emit "cbuf.set_insts_mark();" on every Node::emit method which result in methods like the one below.

```
void loadConNNode::emit(CodeBuffer& cbuf, PhaseRegAlloc* ra_) const {
  cbuf.set_insts_mark();
  // Start at oper_input_base() and count operands
  unsigned idx0 = 1;
  unsigned idx1 = 1; // src
  {
    C2_MacroAssembler _masm(&cbuf);

#line 5832 "/wf/tortugo-jdk/src/hotspot/cpu/x86/x86_64.ad"

    address con = (address)opnd_array(1)->constant();
    if (con == NULL) {
      ShouldNotReachHere();
    } else {
      __ set_narrow_oop(opnd_array(0)->as_Register(ra_,this)/* dst */, (jobject)opnd_array(1)->constant());
    }
  
#line 999999
  }
}
```
IF the definition of the matched instruction (in the AD file) only uses MacroAssembler to emit instructions then we don't need `cbuf.set_insts` in the ::emit method.

This is a clean up that I might would be useful to make before we convert the "::emit" methods to receive "masm" as parameter instead of instantiating one (see parent issue).