Stop using SDK summary bundle. Analyze dart:xxx as any other libraries.

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

Index: pkg/analysis_server/lib/src/services/completion/dart/combinator_contributor.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/combinator_contributor.dart b/pkg/analysis_server/lib/src/services/completion/dart/combinator_contributor.dart
index 4010ece7e2ca87c273b6c83a6a386c97feae51d5..9b2dbb1f46fc486f1e3eafa13a75b1eb95bd5237 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/combinator_contributor.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/combinator_contributor.dart
@@ -26,6 +26,9 @@ class CombinatorContributor extends DartCompletionContributor {
       return EMPTY_LIST;
     }
 
+    // TODO(scheglov) Not sure why we need this now.
+    await request.resolveImports();
+
     // Build list of suggestions
     var directive = node.getAncestor((parent) => parent is NamespaceDirective);
     if (directive is NamespaceDirective) {