Cleanup some unused code in some of the tests

pkg/analysis_server/test/services/dependencies/library_dependencies_test.dart

Index: pkg/analysis_server/test/services/dependencies/library_dependencies_test.dart
diff --git a/pkg/analysis_server/test/services/dependencies/library_dependencies_test.dart b/pkg/analysis_server/test/services/dependencies/library_dependencies_test.dart
index 157bd1da1514c8b580ab54582787bb0b1b46a144..1bede6311a578f2e161fa1ed9b6bb75540c92e49 100644
--- a/pkg/analysis_server/test/services/dependencies/library_dependencies_test.dart
+++ b/pkg/analysis_server/test/services/dependencies/library_dependencies_test.dart
@@ -26,10 +26,7 @@ class LibraryDependenciesTest extends AbstractContextTest {
     provider.newFile('/lib5.dart', 'import "lib6.dart";');
     provider.newFile('/lib6.dart', '');
 
-    _performAnalysis();
-
-    var libs =
-        new LibraryDependencyCollector([context]).collectLibraryDependencies();
+    var libs = new LibraryDependencyCollector([]).collectLibraryDependencies();
 
     // Cycles
     expect(libs, contains('/lib1.dart'));
@@ -46,8 +43,4 @@ class LibraryDependenciesTest extends AbstractContextTest {
   test_PackageMaps() {
     //TODO(pquitslund): add test
   }
-
-  void _performAnalysis() {
-    while (context.performAnalysisTask().hasMoreWork) {}
-  }
 }