Merge the dart:uri library into dart:core and update the Uri class

tests/compiler/dart2js/type_equals_test.dart

Index: tests/compiler/dart2js/type_equals_test.dart
diff --git a/tests/compiler/dart2js/type_equals_test.dart b/tests/compiler/dart2js/type_equals_test.dart
index adf43c0554072f55bda2933f419efa590919a52d..0c283dbeac2cea536baae689a13c08a7a596cc17 100644
--- a/tests/compiler/dart2js/type_equals_test.dart
+++ b/tests/compiler/dart2js/type_equals_test.dart
@@ -50,7 +50,7 @@ bool test(compiler, String name1, String name2, {bool expect}) {
 }
 
 void main() {
-  var uri = new Uri.fromComponents(scheme: 'source');
+  var uri = new Uri(scheme: 'source');
   var compiler = compilerFor(
       r"""
       typedef int Typedef1<X,Y>(String s1);