Stop using deprecated Throws matcher (#38)

diff --git a/lib/src/backends/record_replay/replay_file.dart b/lib/src/backends/record_replay/replay_file.dart
index fa5faf8..1995f31 100644
--- a/lib/src/backends/record_replay/replay_file.dart
+++ b/lib/src/backends/record_replay/replay_file.dart
@@ -24,7 +24,6 @@
     Converter<String, String> blobToString = blobToBytes.fuse(UTF8.decoder);
     Converter<String, RandomAccessFile> reviveRandomAccessFile =
         new ReviveRandomAccessFile(fileSystem);
-    // TODO(tvolkert) remove `as`: https://github.com/dart-lang/sdk/issues/28748
     Converter<String, List<String>> lineSplitter =
         const LineSplitter() as Converter<String, List<String>>;
     Converter<String, List<String>> blobToLines =
diff --git a/lib/src/testing/core_matchers.dart b/lib/src/testing/core_matchers.dart
index 92c701f..b6868e9 100644
--- a/lib/src/testing/core_matchers.dart
+++ b/lib/src/testing/core_matchers.dart
@@ -49,7 +49,7 @@
 /// [message] may be a String, a predicate function, or a [Matcher]. If it is
 /// a String, it will be wrapped in an equality matcher.
 Matcher throwsFileSystemException([dynamic message]) =>
-    new Throws(isFileSystemException(message));
+    throwsA(isFileSystemException(message));
 
 /// Expects the specified [callback] to throw a [FileSystemException] with the
 /// specified [message].
diff --git a/lib/src/testing/record_replay_matchers.dart b/lib/src/testing/record_replay_matchers.dart
index c3cfbce..021940d 100644
--- a/lib/src/testing/record_replay_matchers.dart
+++ b/lib/src/testing/record_replay_matchers.dart
@@ -54,8 +54,7 @@
 
 /// A matcher that successfully matches against a future or function
 /// that throws a [NoMatchingInvocationError].
-const Matcher throwsNoMatchingInvocationError =
-    const Throws(isNoMatchingInvocationError);
+Matcher throwsNoMatchingInvocationError = throwsA(isNoMatchingInvocationError);
 
 /// Base class for matchers that match against generic [InvocationEvent]
 /// instances.
diff --git a/test/recording_test.dart b/test/recording_test.dart
index 99bb54a..1cec320 100644
--- a/test/recording_test.dart
+++ b/test/recording_test.dart
@@ -930,5 +930,5 @@
 }
 
 /// Successfully matches against a function that throws a [TimeoutException].
-const Matcher throwsTimeoutException =
-    const Throws(const isInstanceOf<TimeoutException>());
+Matcher throwsTimeoutException =
+    throwsA(const isInstanceOf<TimeoutException>());