Remove warnings from dart2js test-suite.

tests/compiler/dart2js/metadata_test.dart

Index: tests/compiler/dart2js/metadata_test.dart
diff --git a/tests/compiler/dart2js/metadata_test.dart b/tests/compiler/dart2js/metadata_test.dart
index ab302ebf960390b577db4f90d0068c9fdb86c55b..1c7f596f7e751c3dd7e83333c3f3884eab53ab7d 100644
--- a/tests/compiler/dart2js/metadata_test.dart
+++ b/tests/compiler/dart2js/metadata_test.dart
@@ -6,6 +6,8 @@ import "package:expect/expect.dart";
 import "package:async_helper/async_helper.dart";
 import 'compiler_helper.dart';
 import 'parser_helper.dart';
+import '../../../sdk/lib/_internal/compiler/implementation/dart2jslib.dart'
+    show PrimitiveConstant;
 
 void checkPosition(Spannable spannable, Node node, String source, compiler) {
   SourceSpan span = compiler.spanFromSpannable(spannable);
@@ -34,7 +36,7 @@ void checkAnnotation(String name, String declaration,
         'Unexpected metadata count on $element.');
     PartialMetadataAnnotation annotation = element.metadata.head;
     annotation.ensureResolved(compiler);
-    Constant value = annotation.value;
+    PrimitiveConstant value = annotation.value;
     Expect.stringEquals('xyz', value.value.slowToString());
 
     checkPosition(annotation, annotation.cachedNode, source1, compiler);
@@ -57,8 +59,8 @@ void checkAnnotation(String name, String declaration,
     Expect.isFalse(identical(annotation1, annotation2),
                    'expected unique instances');
     Expect.notEquals(annotation1, annotation2, 'expected unequal instances');
-    Constant value1 = annotation1.value;
-    Constant value2 = annotation2.value;
+    PrimitiveConstant value1 = annotation1.value;
+    PrimitiveConstant value2 = annotation2.value;
     Expect.identical(value1, value2, 'expected same compile-time constant');
     Expect.stringEquals('xyz', value1.value.slowToString());
     Expect.stringEquals('xyz', value2.value.slowToString());
@@ -87,7 +89,7 @@ void checkAnnotation(String name, String declaration,
     Expect.equals(1, length(element.metadata));
     PartialMetadataAnnotation annotation = element.metadata.head;
     annotation.ensureResolved(compiler);
-    Constant value = annotation.value;
+    PrimitiveConstant value = annotation.value;
     Expect.stringEquals('xyz', value.value.slowToString());
 
     checkPosition(annotation, annotation.cachedNode, source3, compiler);
@@ -116,8 +118,8 @@ void checkAnnotation(String name, String declaration,
     Expect.isFalse(identical(annotation1, annotation2),
                    'expected unique instances');
     Expect.notEquals(annotation1, annotation2, 'expected unequal instances');
-    Constant value1 = annotation1.value;
-    Constant value2 = annotation2.value;
+    PrimitiveConstant value1 = annotation1.value;
+    PrimitiveConstant value2 = annotation2.value;
     Expect.identical(value1, value2, 'expected same compile-time constant');
     Expect.stringEquals('xyz', value1.value.slowToString());
     Expect.stringEquals('xyz', value2.value.slowToString());
@@ -169,7 +171,7 @@ void testLibraryTags() {
 
       PartialMetadataAnnotation annotation = metadata.head;
       annotation.ensureResolved(compiler);
-      Constant value = annotation.value;
+      PrimitiveConstant value = annotation.value;
       Expect.stringEquals('xyz', value.value.slowToString());
 
       checkPosition(annotation, annotation.cachedNode, source, compiler);