Can’t use isA until we drop support for Dart 1

Author: aaronlademann-wf

test/integration/copy_license_test.dart

@@ -79,7 +79,7 @@ void main() {
   group('Copy License Task', () {
     test('should warn if the license file does not exist', () async {
       expect(copyLicense(projectWithoutLicenseFile),
-          throwsA(isA<NoLicenseFileException>()));
+          throwsA(const isInstanceOf<NoLicenseFileException>()));
     });
 
     test('should not apply license to files that already have it', () async {

test/integration/export_config_test.dart

@@ -51,7 +51,7 @@ void main() {
         json = convert.json.decode(output);
       }, returnsNormally);
 
-      expect(json, isA<Map>());
+      expect(json, const isInstanceOf<Map>());
     });
 
     test('should emit JSON with default config for projects without a dev.dart',

test/integration/test_test.dart

@@ -153,12 +153,12 @@ void main() {
   group('Test Task', () {
     test('should fail if some unit tests fail', () async {
       expect(runTests(projectWithFailingTests, unit: true, integration: false),
-          throwsA(isA<TestFailure>()));
+          throwsA(const isInstanceOf<TestFailure>()));
     });
 
     test('should fail if some integration tests fail', () async {
       expect(runTests(projectWithFailingTests, unit: false, integration: true),
-          throwsA(isA<TestFailure>()));
+          throwsA(const isInstanceOf<TestFailure>()));
     });
 
     test('should run individual unit test', () async {
@@ -206,7 +206,8 @@ void main() {
     });
 
     test('should warn if "test" package is not immediate dependency', () async {
-      expect(runTests(projectWithoutTestPackage), throwsA(isA<TestFailure>()));
+      expect(runTests(projectWithoutTestPackage),
+          throwsA(const isInstanceOf<TestFailure>()));
     });
 
     test('should run tests that require a Pub server', () async {
@@ -227,7 +228,7 @@ void main() {
 
     test('should fail if named test does not exist', () async {
       expect(runTests(projectWithPassingTests, testName: 'non-existent test'),
-          throwsA(isA<TestFailure>()));
+          throwsA(const isInstanceOf<TestFailure>()));
     });
 
     test('should allow you to specify a web-compiler', () async {
@@ -253,12 +254,12 @@ void main() {
 
     test('should fail if using dartium on Dart2', () async {
       expect(runTests(projectWithPassingTests, platform: 'dartium'),
-          throwsA(isA<TestFailure>()));
+          throwsA(const isInstanceOf<TestFailure>()));
     }, tags: 'dart2-only');
 
     test('should fail if using content-shell on Dart2', () async {
       expect(runTests(projectWithPassingTests, platform: 'content-shell'),
-          throwsA(isA<TestFailure>()));
+          throwsA(const isInstanceOf<TestFailure>()));
     }, tags: 'dart2-only');
 
     test('should not fail if using dartium on Dart1', () async {