length doesn't need an extension method

[jmesserly]

The JS impl is exactly same signature/result as Dart.

  int get length => JS('JSUInt32', r'#.length', this);

(source: JSArray in dart2js)

[jmesserly]

Funny, although now that I look, the setter is a bit different. Nevermind :)

[jmesserly]

well, we could generate the reads as list.length though. Maybe still worth a special case?

fyi setter is:

  void set length(int newLength) {
    if (newLength is !int) throw new ArgumentError(newLength);
    if (newLength < 0) throw new RangeError.value(newLength);
    checkGrowable('set length');
    JS('void', r'#.length = #', this, newLength);
  }

The is! int checks and <0 checks probably we don't need, but the checkGrowable seems needed. That said, Arrays can be subclassed in ES6 so maybe we could implement non-growable that way.

[jmesserly]

related: #138

[jmesserly]

fyi @rakudrama just hit this. maybe we regressed .length special case at some point?

[jmesserly]

going to close this out, if we hit again in perf investigations we can reopen