Store the async-await compiled pub code directly in the repo.

sdk/lib/_internal/pub_generated/bin/async_compile.dart

+import 'dart:io';
+import 'package:args/args.dart';
+import 'package:analyzer/src/services/formatter_impl.dart';
+import 'package:async_await/async_await.dart' as async_await;
+import 'package:path/path.dart' as p;
+final sourceDir = p.dirname(p.dirname(p.fromUri(Platform.script)));
+final sourceUrl = p.toUri(sourceDir).toString();
+final generatedDir = p.join(p.dirname(sourceDir), 'pub_generated');
+bool hadFailure = false;
+bool verbose = false;
+final _compilerPattern = new RegExp(r"import '(\.\./)+compiler");
+final _commitPattern = new RegExp(r"[a-f0-9]{40,40}");
+void main(List<String> arguments) {
+  var parser = new ArgParser(allowTrailingOptions: true);
+  parser.addFlag("verbose", callback: (value) => verbose = value);
+  var force = false;
+  parser.addFlag("force", callback: (value) => force = value);
+  var buildDir;
+  try {
+    var rest = parser.parse(arguments).rest;
+    if (rest.isEmpty) {
+      throw new FormatException('Missing build directory.');
+    } else if (rest.length > 1) {
+      throw new FormatException(
+          'Unexpected arguments: ${rest.skip(1).join(" ")}.');
+    }
+    buildDir = rest.first;
+  } on FormatException catch (ex) {
+    stderr.writeln(ex);
+    stderr.writeln();
+    stderr.writeln(
+        "Usage: dart async_compile.dart [--verbose] [--force] <build dir>");
+    exit(64);
+  }
+  var result = Process.runSync(
+      "git",
+      ["rev-parse", "HEAD"],
+      workingDirectory: p.join(sourceDir, "../../../../third_party/pkg/async_await"));
+  if (result.exitCode != 0) {
+    stderr.writeln("Could not get Git revision of async_await compiler.");
+    exit(1);
+  }
+  var currentCommit = result.stdout.trim();
+  var readmePath = p.join(generatedDir, "README.md");
+  var lastCommit;
+  var readme = new File(readmePath).readAsStringSync();
+  var match = _commitPattern.firstMatch(readme);
+  if (match == null) {
+    stderr.writeln("Could not find compiler commit hash in README.md.");
+    exit(1);
+  }
+  lastCommit = match[0];
+  var numFiles = 0;
+  var numCompiled = 0;
+  for (var entry in new Directory(sourceDir).listSync(recursive: true)) {
+    if (p.extension(entry.path) != ".dart") continue;
+    numFiles++;
+    var relative = p.relative(entry.path, from: sourceDir);
+    var sourceFile = entry as File;
+    var destPath = p.join(generatedDir, relative);
+    var destFile = new File(destPath);
+    if (force ||
+        currentCommit != lastCommit ||
+        !destFile.existsSync() ||
+        entry.lastModifiedSync().isAfter(destFile.lastModifiedSync())) {
+      _compile(sourceFile.path, sourceFile.readAsStringSync(), destPath);
+      numCompiled++;
+      if (verbose) print("Compiled $relative");
+    }
+  }
+  if (currentCommit != lastCommit) {
+    readme = readme.replaceAll(_commitPattern, currentCommit);
+    _writeFile(readmePath, readme);
+  }
+  if (verbose) print("Compiled $numCompiled out of $numFiles files");
+  if (numCompiled > 0) _generateSnapshot(buildDir);
+  if (hadFailure) exit(1);
+}
+void _compile(String sourcePath, String source, String destPath) {
+  var destDir = new Directory(p.dirname(destPath));
+  destDir.createSync(recursive: true);
+  source = _translateAsyncAwait(sourcePath, source);
+  if (source != null) source = _fixDart2jsImports(sourcePath, source, destPath);
+  if (source == null) {
+    _deleteFile(destPath);
+  } else {
+    _writeFile(destPath, source);
+  }
+}
+String _translateAsyncAwait(String sourcePath, String source) {
+  if (p.isWithin(p.join(sourceDir, "asset"), sourcePath)) {
+    return source;
+  }
+  try {
+    source = async_await.compile(source);
+    var result = new CodeFormatter().format(CodeKind.COMPILATION_UNIT, source);
+    return result.source;
+  } catch (ex) {
+    stderr.writeln("Async compile failed on $sourcePath:\n$ex");
+    hadFailure = true;
+    return null;
+  }
+}
+String _fixDart2jsImports(String sourcePath, String source, String destPath) {
+  var compilerDir = p.url.join(sourceUrl, "../compiler");
+  var relative = p.url.relative(compilerDir, from: p.dirname(destPath));
+  return source.replaceAll(_compilerPattern, "import '$relative");
+}
+void _generateSnapshot(String buildDir) {
+  buildDir = p.normalize(buildDir);
+  var entrypoint = p.join(generatedDir, 'bin/pub.dart');
+  var packageRoot = p.join(buildDir, 'packages');
+  var snapshot = p.join(buildDir, 'dart-sdk/bin/snapshots/pub.dart.snapshot');
+  var result = Process.runSync(
+      Platform.executable,
+      ["--package-root=$packageRoot", "--snapshot=$snapshot", entrypoint]);
+  if (result.exitCode != 0) {
+    stderr.writeln("Failed to generate snapshot:");
+    if (result.stderr.trim().isNotEmpty) stderr.writeln(result.stderr);
+    if (result.stdout.trim().isNotEmpty) stderr.writeln(result.stdout);
+    exit(result.exitCode);
+  }
+  if (verbose) print("Created pub snapshot");
+}
+void _deleteFile(String path) {
+  try {
+    new File(path).deleteSync();
+  } on IOException catch (ex) {}
+}
+void _writeFile(String path, String contents) {
+  try {
+    new File(path).writeAsStringSync(contents);
+  } on IOException catch (ex) {}
+}