Change Enqueuer to use Entity instead of Element.

tests/compiler/dart2js/resolution_test.dart

Index: tests/compiler/dart2js/resolution_test.dart
diff --git a/tests/compiler/dart2js/resolution_test.dart b/tests/compiler/dart2js/resolution_test.dart
index cfca9a8797a369117853cd48340de54d2a8d9888..8ad71c2af30c7a38871bcbbc58088d808238b518 100644
--- a/tests/compiler/dart2js/resolution_test.dart
+++ b/tests/compiler/dart2js/resolution_test.dart
@@ -103,14 +103,16 @@ void test(String code, void check(CompilerImpl compiler)) {
 void testHasRuntimeType(String code) {
   test(code, (compiler) {
     var element = compiler.backend.helpers.createRuntimeType;
-    Expect.isTrue(compiler.enqueuer.resolution.isProcessed(element));
+    Expect.isTrue(
+        compiler.enqueuer.resolution.processedEntities.contains(element));
   });
 }
 
 main() {
   test(NO_RUNTIME_TYPE, (compiler) {
     var element = compiler.backend.helpers.createRuntimeType;
-    Expect.isFalse(compiler.enqueuer.resolution.isProcessed(element));
+    Expect.isFalse(
+        compiler.enqueuer.resolution.processedEntities.contains(element));
   });
 
   testHasRuntimeType(HAS_RUNTIME_TYPE_1);