simplify contributors by resolving declarations in scope

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 8696b924d64942b53664d32ccc20830554e85b3b..a08b8bb30c0fa66fc2079aea8c7f1ee73546f27d 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
@@ -26,20 +26,6 @@ class CombinatorContributor extends DartCompletionContributor {
       return EMPTY_LIST;
     }
 
-    // Partially resolve the compilation unit
-    CompilationUnit unit = await request.resolveDeclarationsInScope();
-    // Gracefully degrade if the compilation unit could not be resolved
-    // e.g. detached part file or source change
-    if (unit == null) {
-      return EMPTY_LIST;
-    }
-
-    // Check the target since resolution may have changed it
-    node = request.target.containingNode;
-    if (node is! Combinator) {
-      return EMPTY_LIST;
-    }
-
     // Build list of suggestions
     var directive = node.getAncestor((parent) => parent is NamespaceDirective);
     if (directive is NamespaceDirective) {