Migrate tests to using package test

BUG=
R=rnystrom@google.com

Review-Url: https://codereview.chromium.org//2979043002 .
diff --git a/pubspec.yaml b/pubspec.yaml
index 96ccfa0..185275f 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -4,6 +4,6 @@
 description: Library for 32- and 64-bit signed fixed-width integers.
 homepage: https://github.com/dart-lang/fixnum
 dev_dependencies:
-  unittest: ">=0.9.0 <0.12.0"
+  test: ^0.12.0
 environment:
   sdk: ">=0.8.10+6 <2.0.0"
diff --git a/test/int32_test.dart b/test/int32_test.dart
index df95894..d237a03 100644
--- a/test/int32_test.dart
+++ b/test/int32_test.dart
@@ -5,7 +5,7 @@
 library Int32test;
 
 import 'package:fixnum/fixnum.dart';
-import 'package:unittest/unittest.dart';
+import 'package:test/test.dart';
 
 void main() {
   group("isX tests", () {
diff --git a/test/int64_test.dart b/test/int64_test.dart
index c449822..1ea7e75 100644
--- a/test/int64_test.dart
+++ b/test/int64_test.dart
@@ -5,7 +5,7 @@
 library int64test;
 
 import 'package:fixnum/fixnum.dart';
-import 'package:unittest/unittest.dart';
+import 'package:test/test.dart';
 
 void main() {
   group("fromBytes", () {
@@ -129,13 +129,13 @@
       expect(new Int64(100) * Int64.ZERO, Int64.ZERO);
 
       expect(new Int64.fromInts(0x12345678, 0x12345678) *
-              new Int64.fromInts(0x1234, 0x12345678),
+          new Int64.fromInts(0x1234, 0x12345678),
           new Int64.fromInts(0x7ff63f7c, 0x1df4d840));
       expect(new Int64.fromInts(0xf2345678, 0x12345678) *
-              new Int64.fromInts(0x1234, 0x12345678),
+          new Int64.fromInts(0x1234, 0x12345678),
           new Int64.fromInts(0x7ff63f7c, 0x1df4d840));
       expect(new Int64.fromInts(0xf2345678, 0x12345678) *
-              new Int64.fromInts(0xffff1234, 0x12345678),
+          new Int64.fromInts(0xffff1234, 0x12345678),
           new Int64.fromInts(0x297e3f7c, 0x1df4d840));
 
       // RHS Int32
@@ -203,16 +203,16 @@
       expect(new Int64(-1000) ~/ new Int64(-3), new Int64(333));
       expect(new Int64(3) ~/ new Int64(1000), Int64.ZERO);
       expect(new Int64.fromInts(0x12345678, 0x12345678) ~/
-              new Int64.fromInts(0x0, 0x123),
+          new Int64.fromInts(0x0, 0x123),
           new Int64.fromInts(0x1003d0, 0xe84f5ae8));
       expect(new Int64.fromInts(0x12345678, 0x12345678) ~/
-              new Int64.fromInts(0x1234, 0x12345678),
+          new Int64.fromInts(0x1234, 0x12345678),
           new Int64.fromInts(0x0, 0x10003));
       expect(new Int64.fromInts(0xf2345678, 0x12345678) ~/
-              new Int64.fromInts(0x1234, 0x12345678),
+          new Int64.fromInts(0x1234, 0x12345678),
           new Int64.fromInts(0xffffffff, 0xffff3dfe));
       expect(new Int64.fromInts(0xf2345678, 0x12345678) ~/
-              new Int64.fromInts(0xffff1234, 0x12345678),
+          new Int64.fromInts(0xffff1234, 0x12345678),
           new Int64.fromInts(0x0, 0xeda));
       expect(new Int64(829893893) ~/ new Int32(1919), new Int32(432461));
       expect(new Int64(829893893) ~/ new Int64(1919), new Int32(432461));