swift234

stdlib: Do the Array fast-path check with a single array property call.

Now that we can check isNative and NoDTC (no deffered type check needed) with a single bit-mask operation,
it makes sense to have a single array property call for it.
I replaced the the semantics call array.props.needsElementTypeCheck with array.props.isNativeNoDTC,
which is the combination of isNative && !needsElementTypeCheck. I kept array.props.isNative, which is not used for now,
but might be useful in the future, e.g. for array operations which don't care about type checks.

The optimized SIL for a class array access arr[i] now contains the minimum of 4 basic blocks.
PerfTests show +25% for DeltaBlue and some improvemements for -Onone.



Swift SVN r26871