Change the way tasks are registered

pkg/analyzer/lib/src/context/context.dart

Index: pkg/analyzer/lib/src/context/context.dart
diff --git a/pkg/analyzer/lib/src/context/context.dart b/pkg/analyzer/lib/src/context/context.dart
index 0faff27f7977cbabc80e997fa9a92e635bce255d..132efd1ea7f2dc3ab17dd1b6df5626e33fcc34dc 100644
--- a/pkg/analyzer/lib/src/context/context.dart
+++ b/pkg/analyzer/lib/src/context/context.dart
@@ -240,6 +240,7 @@ class AnalysisContextImpl implements InternalAnalysisContext {
    * Initialize a newly created analysis context.
    */
   AnalysisContextImpl() {
+    AnalysisEngine.instance.processRequiredPlugins();
     _privatePartition = new UniversalCachePartition(this);
     _cache = createCacheFromSourceFactory(null);
     _taskManager = AnalysisEngine.instance.taskManager;