Fix some runtime check failures in tests

Fix some Dart 2 runtime check failures due to inferred List<dynamic>.

Change-Id: I09215629d4d6c70cd56930b0d19de2a092a7facd
Reviewed-on: https://dart-review.googlesource.com/58208
Reviewed-by: Dmitry Stefantsov <dmitryas@google.com>
Commit-Queue: Kevin Millikin <kmillikin@google.com>
diff --git a/pkg/front_end/test/scanner_test.dart b/pkg/front_end/test/scanner_test.dart
index d03ee59..3878155 100644
--- a/pkg/front_end/test/scanner_test.dart
+++ b/pkg/front_end/test/scanner_test.dart
@@ -1279,7 +1279,7 @@
       new StringToken(TokenType.STRING, "", 3),
       new StringToken(TokenType.STRING_INTERPOLATION_IDENTIFIER, "\$", 3),
     ];
-    var expectedErrors = [];
+    var expectedErrors = <TestError>[];
     if (usingFasta) {
       // Fasta scanner inserts a synthetic identifier
       expectedTokens.addAll([
@@ -1305,7 +1305,7 @@
       new StringToken(TokenType.STRING, "'", 0),
       new StringToken(TokenType.STRING_INTERPOLATION_IDENTIFIER, "\$", 1),
     ];
-    var expectedErrors = [];
+    var expectedErrors = <TestError>[];
     if (usingFasta) {
       expectedTokens.addAll([
         new SyntheticStringToken(TokenType.IDENTIFIER, "", 2),
diff --git a/pkg/kernel/test/class_hierarchy_test.dart b/pkg/kernel/test/class_hierarchy_test.dart
index 439da52..2327eca 100644
--- a/pkg/kernel/test/class_hierarchy_test.dart
+++ b/pkg/kernel/test/class_hierarchy_test.dart
@@ -237,7 +237,7 @@
     var supertype =
         extends_ != null ? extends_(typeParameterTypes) : objectSuper;
     var implementedTypes =
-        implements_ != null ? implements_(typeParameterTypes) : [];
+        implements_ != null ? implements_(typeParameterTypes) : <Supertype>[];
     return addClass(new Class(
         name: name,
         typeParameters: typeParameters,