Use a mock SDK for most analysis server tests.

pkg/analysis_server/test/analysis_abstract.dart

Index: pkg/analysis_server/test/analysis_abstract.dart
diff --git a/pkg/analysis_server/test/analysis_abstract.dart b/pkg/analysis_server/test/analysis_abstract.dart
index 2ea2e1dc6c31bac1dcbdaae4644d29021b5066f1..358b54d84c069c02a4a1796f715aaf6a4d43d673 100644
--- a/pkg/analysis_server/test/analysis_abstract.dart
+++ b/pkg/analysis_server/test/analysis_abstract.dart
@@ -44,6 +44,7 @@ class AbstractAnalysisTest {
     serverChannel = new MockServerChannel();
     resourceProvider = new MemoryResourceProvider();
     server = new AnalysisServer(serverChannel, resourceProvider);
+    server.defaultSdk = new MockSdk();
     handler = new AnalysisDomainHandler(server);
     // listen for notifications
     Stream<Notification> notificationStream = serverChannel.notificationController.stream;