Add a dev dependency on fibers from NPM

.gitignore

@@ -8,3 +8,4 @@ packages
 .packages
 pubspec.lock
 /benchmark/source
+node_modules/

.travis.yml

@@ -43,7 +43,7 @@ install:
 - if-node . "$HOME/.nvm/nvm.sh"
 - if-node nvm install "$NODE_VERSION"
 - if-node nvm use "$NODE_VERSION"
-- SASS_MINIFY_JS=false if-node pub run grinder npm_package
+- SASS_MINIFY_JS=false if-node pub run grinder before_test
 
 # Download sass-spec and install its dependencies if we're running specs.
 - if-specs() { if [ "$TASK" = specs ]; then "$@"; fi }

package.json

@@ -0,0 +1,9 @@
+{
+  "//": [
+    "This isn't the official package.json for Dart Sass. It's just used to ",
+    "install dependencies used for testing the Node API."
+  ],
+  "devDependencies": {
+    "fibers": ">=1.0.0 <3.0.0"
+  }
+}

pubspec.yaml

@@ -36,6 +36,6 @@ dev_dependencies:
   stream_channel: "^1.0.0"
   test_descriptor: "^1.0.0"
   test_process: "^1.0.0-rc.1"
-  test: "^0.12.26"
+  test: "^0.12.29"
   xml: "^2.4.0"
   yaml: "^2.0.0"

test/ensure_npm_package.dart

@@ -32,7 +32,7 @@ hybridMain(StreamChannel channel) async {
       var entryLastModified = entry.lastModifiedSync();
       if (lastModified.isBefore(entryLastModified)) {
         throw "${entry.path} was modified after NPM package was generated.\n"
-            "Run pub run grinder npm_package.";
+            "Run pub run grinder before_test.";
       }
     }
   }

tool/grind.dart

@@ -38,10 +38,8 @@ final _sdkDir = p.dirname(p.dirname(Platform.resolvedExecutable));
 main(List<String> args) => grind(args);
 
 @DefaultTask('Compile async code and reformat.')
-all() {
+@Depends(format, synchronize)
-  format();
+all() {}
-  synchronize();
-}
 
 @Task('Run the Dart formatter.')
 format() {
@@ -100,6 +98,13 @@ npm_package() {
   _writeNpmPackage('build/npm-old', json..addAll({"name": "dart-sass"}));
 }
 
+@Task('Installs dependencies from npm.')
+npm_install() => run("npm", arguments: ["install"]);
+
+@Task('Runs the tasks that are required for running tests.')
+@Depends(npm_package, npm_install)
+before_test() {}
+
 /// Writes a Dart Sass NPM package to the directory at [destination].
 ///
 /// The [json] will be used as the package's package.json.