Watcher should use Directory.watch

[DartBot]

<img src="https://avatars.githubusercontent.com/u/188?v=3" align="left" width="96" height="96"hspace="10"> Issue by nex3
Originally opened as dart-lang/sdk#14428

---

The polling watcher is very inefficient and memory-hungry, and is likely contributing towards issue dart-lang/pub#647. Now that dart:io exposes native watchers, we should use them where possible.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/188?v=3" align="left" width="48" height="48"hspace="10"> Comment by nex3

---

Marked this as blocking dart-lang/pub#647.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/188?v=3" align="left" width="48" height="48"hspace="10"> Comment by nex3

---

dart-lang/sdk@500eb12 adds support for [Directory.watch] on Linux, and dart-lang/sdk@03337e9 adds it on Mac OS. Now only Windows remains.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/188?v=3" align="left" width="48" height="48"hspace="10"> Comment by nex3

---

Added Accepted label.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/4865287?v=3" align="left" width="48" height="48"hspace="10"> Comment by lrhn

---

Removed Area-Library label.
Added Area-Pkg label.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/3276024?v=3" align="left" width="48" height="48"hspace="10"> Comment by anders-sandholm

---

Removed Library-Watcher label.
Added Pkg-Watcher label.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/46275?v=3" align="left" width="48" height="48"hspace="10"> Comment by munificent

---

Lowering the priority. The polling watcher doesn't use as much memory now. It would still be good to use the native watcher support, but it's not a burning issue.

---

Removed Type-Defect, Priority-High labels.
Added Type-Enhancement, Priority-Medium labels.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2156198?v=3" align="left" width="48" height="48"hspace="10"> Comment by kasperl

---

Removed this from the M8 milestone.
Added this to the 1.6 milestone.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/46275?v=3" align="left" width="48" height="48"hspace="10"> Comment by munificent

---

Marked this as being blocked by dart-lang/pub#1002.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/22043?v=3" align="left" width="48" height="48"hspace="10"> Comment by skabet

---

Landed native watching for Windows in dart-lang/sdk@146f951 + followups. While there may still may be tweaks to be made, it passes all current tests.

---

Added Fixed label.