Duplicate implementation of dprecision_rounding and dstore_rounding

The following two methods are duplicate.
It would be better to remove one.

```
// rounding for strict double precision conformance
Node* GraphKit::dprecision_rounding(Node *n) {
  if (Matcher::strict_fp_requires_explicit_rounding) {
#ifdef IA32
    if (UseSSE < 2) {
      return _gvn.transform(new RoundDoubleNode(0, n));
    }
#else
    Unimplemented();
#endif // IA32
  }
  return n;
}

// rounding for non-strict double stores
Node* GraphKit::dstore_rounding(Node* n) {
  if (Matcher::strict_fp_requires_explicit_rounding) {
#ifdef IA32
    if (UseSSE < 2) {
      return _gvn.transform(new RoundDoubleNode(0, n));
    }
#else
    Unimplemented();
#endif // IA32
  }
  return n;
}
```