Fix checked mode break in server mode

lib/src/server/server.dart

Index: lib/src/server/server.dart
diff --git a/lib/src/server/server.dart b/lib/src/server/server.dart
index 89a5ab608c4092133d91047b4cc75c481d9a3af6..123b0a0bbc142e592a6dc34707ba663c3060e83e 100644
--- a/lib/src/server/server.dart
+++ b/lib/src/server/server.dart
@@ -53,7 +53,8 @@ class ServerCompiler extends AbstractCompiler {
                 ? SourceResolverOptions.implicitHtmlFile
                 : inputFile)));
     var graph = new SourceGraph(context, reporter, options);
-    var entryNodes = inputUris.map((inputUri) => graph.nodeFromUri(inputUri));
+    var entryNodes =
+        inputUris.map((inputUri) => graph.nodeFromUri(inputUri)).toList();
 
     return new ServerCompiler._(context, options, reporter, graph, entryNodes);
   }