Fixes for URI and Object completions with the new driver.

pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart

Index: pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart b/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
index 069b07196d7a2988399a2957ddf8f7ef943df1b8..ea320bebe3d8ef1e3a027241b73a976d7028e465 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
@@ -177,8 +177,11 @@ class DartCompletionRequestImpl implements DartCompletionRequest {
 
   @override
   LibraryElement get coreLib {
-    if (_coreLib == null) {
-      Source coreUri = context.sourceFactory.forUri('dart:core');
+    if (result != null) {
+      AnalysisContext context = result.unit.element.context;
+      _coreLib = context.typeProvider.objectType.element.library;
+    } else {
+      Source coreUri = sourceFactory.forUri('dart:core');
       _coreLib = context.computeLibraryElement(coreUri);
     }
     return _coreLib;
@@ -222,6 +225,11 @@ class DartCompletionRequestImpl implements DartCompletionRequest {
     return _opType;
   }
 
+  @override
+  SourceFactory get sourceFactory {
+    return context?.sourceFactory ?? result.sourceFactory;
+  }
+
   /**
    * Throw [AbortCompletion] if the completion request has been aborted.
    */