Adding Angular's DI package & Dart unittests which test it.

third_party/pkg/di/lib/dynamic_injector.dart

Index: third_party/pkg/di/lib/dynamic_injector.dart
diff --git a/third_party/pkg/di/lib/dynamic_injector.dart b/third_party/pkg/di/lib/dynamic_injector.dart
new file mode 100644
index 0000000000000000000000000000000000000000..53ec52eec24922f63e40abf464ef30920fbbc416
--- /dev/null
+++ b/third_party/pkg/di/lib/dynamic_injector.dart
@@ -0,0 +1,64 @@
+library di.dynamic_injector;
+
+import 'di.dart';
+import 'mirrors.dart';
+
+/**
+ * Dynamic implementation of [Injector] that uses mirrors.
+ */
+class DynamicInjector extends Injector {
+
+  DynamicInjector({List<Module> modules, String name,
+                  bool allowImplicitInjection: false})
+      : super(modules: modules, name: name,
+          allowImplicitInjection: allowImplicitInjection);
+
+  DynamicInjector._fromParent(List<Module> modules, Injector parent, {name})
+      : super.fromParent(modules, parent, name: name);
+
+  newFromParent(List<Module> modules, String name) {
+    return new DynamicInjector._fromParent(modules, this, name: name);
+  }
+
+  Object newInstanceOf(Type type, ObjectFactory getInstanceByType,
+                       Injector requestor, error) {
+    var classMirror = reflectType(type);
+    if (classMirror is TypedefMirror) {
+      throw new NoProviderError(error('No implementation provided '
+          'for ${getSymbolName(classMirror.qualifiedName)} typedef!'));
+    }
+
+    MethodMirror ctor = classMirror.declarations[classMirror.simpleName];
+
+    resolveArgument(int pos) {
+      ParameterMirror p = ctor.parameters[pos];
+      return getInstanceByType(getReflectedTypeWorkaround(p.type), requestor);
+    }
+
+    var args = new List.generate(ctor.parameters.length, resolveArgument,
+        growable: false);
+    return classMirror.newInstance(ctor.constructorName, args).reflectee;
+  }
+
+  /**
+   * Invoke given function and inject all its arguments.
+   *
+   * Returns whatever the function returns.
+   */
+  dynamic invoke(Function fn) {
+    ClosureMirror cm = reflect(fn);
+    MethodMirror mm = cm.function;
+    int position = 0;
+    List args = mm.parameters.map((ParameterMirror parameter) {
+      try {
+        return get(getReflectedTypeWorkaround(parameter.type));
+      } on NoProviderError catch (e) {
+        throw new NoProviderError(e.message);
+      } finally {
+        position++;
+      }
+    }).toList();
+
+    return cm.apply(args).reflectee;
+  }
+}