Remove upper case constants (#75)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a5ebcfd..2c7d11e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.12.2+1
+
+- Updated SDK version to 2.0.0-dev.17.0
+
 ## 0.12.2
 
 * Fixed `unorderedMatches` in cases where the matchers may match more than one
diff --git a/lib/src/core_matchers.dart b/lib/src/core_matchers.dart
index e8fdb11..0efe4e9 100644
--- a/lib/src/core_matchers.dart
+++ b/lib/src/core_matchers.dart
@@ -74,13 +74,13 @@
 
 class _IsNaN extends Matcher {
   const _IsNaN();
-  bool matches(item, Map matchState) => double.NAN.compareTo(item) == 0;
+  bool matches(item, Map matchState) => double.nan.compareTo(item) == 0;
   Description describe(Description description) => description.add('NaN');
 }
 
 class _IsNotNaN extends Matcher {
   const _IsNotNaN();
-  bool matches(item, Map matchState) => double.NAN.compareTo(item) != 0;
+  bool matches(item, Map matchState) => double.nan.compareTo(item) != 0;
   Description describe(Description description) => description.add('not NaN');
 }
 
diff --git a/pubspec.yaml b/pubspec.yaml
index c898554..f08b2a3 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,10 +1,10 @@
 name: matcher
-version: 0.12.2
+version: 0.12.2+1
 author: Dart Team <misc@dartlang.org>
 description: Support for specifying test expectations
 homepage: https://github.com/dart-lang/matcher
 environment:
-  sdk: '>=1.23.0 <2.0.0'
+  sdk: '>=2.0.0-dev.17.0 <2.0.0'
 dependencies:
   stack_trace: '^1.2.0'
 dev_dependencies:
diff --git a/test/core_matchers_test.dart b/test/core_matchers_test.dart
index 8261c6f..5b24d46 100644
--- a/test/core_matchers_test.dart
+++ b/test/core_matchers_test.dart
@@ -35,13 +35,13 @@
   });
 
   test('isNaN', () {
-    shouldPass(double.NAN, isNaN);
+    shouldPass(double.nan, isNaN);
     shouldFail(3.1, isNaN, "Expected: NaN Actual: <3.1>");
   });
 
   test('isNotNaN', () {
     shouldPass(3.1, isNotNaN);
-    shouldFail(double.NAN, isNotNaN, "Expected: not NaN Actual: <NaN>");
+    shouldFail(double.nan, isNotNaN, "Expected: not NaN Actual: <NaN>");
   });
 
   test('same', () {