Compile JS with --trust-type-annotations.

CHANGELOG.md

@@ -1,3 +1,8 @@
+## 1.0.0-alpha.10
+
+* Trust type annotations when compiling to JavaScript, which makes it
+  substantially faster.
+
 ## 1.0.0-alpha.9
 
 * Elements without a namespace (such as `div`) are no longer unified with

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.0.0-alpha.9
+version: 1.0.0-dev
 description: A Sass implementation in Dart.
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/sass/dart-sass

tool/grind.dart

@@ -58,6 +58,7 @@ js() {
   _ensureBuild();
   var destination = new File('build/sass.dart.js');
   Dart2js.compile(new File('bin/sass.dart'), outFile: destination, extraArgs: [
+    '--trust-type-annotations',
     '-Dnode=true',
     '-Dversion=$_version',
     '-Ddart-version=$_dartVersion',