Make isEmpty a getter.

lib/compiler/implementation/scanner/class_element_parser.dart

Index: lib/compiler/implementation/scanner/class_element_parser.dart
diff --git a/lib/compiler/implementation/scanner/class_element_parser.dart b/lib/compiler/implementation/scanner/class_element_parser.dart
index 0e536d92af5e715d2643f2996b8036edec642b2b..f86720c6a4797233573f6f6ab96b802be667aa46 100644
--- a/lib/compiler/implementation/scanner/class_element_parser.dart
+++ b/lib/compiler/implementation/scanner/class_element_parser.dart
@@ -41,7 +41,7 @@ class PartialClassElement extends ClassElement {
         Token token = parser.parseTopLevelDeclaration(beginToken);
         assert(identical(token, endToken.next));
         cachedNode = listener.popNode();
-        assert(listener.nodes.isEmpty());
+        assert(listener.nodes.isEmpty);
       });
       compiler.patchParser.measure(() {
         if (isPatched) {
@@ -169,7 +169,7 @@ class MemberListener extends NodeListener {
   }
 
   void addMember(Element memberElement) {
-    for (Link link = metadata; !link.isEmpty(); link = link.tail) {
+    for (Link link = metadata; !link.isEmpty; link = link.tail) {
       memberElement.addMetadata(link.head);
     }
     metadata = const Link<MetadataAnnotation>();