Implement 'topLevelLibraryDeclarations' getter to return all libraries with exported top-level decl…

pkg/analyzer/lib/src/dart/analysis/top_level_declaration.dart

Index: pkg/analyzer/lib/src/dart/analysis/top_level_declaration.dart
diff --git a/pkg/analyzer/lib/src/dart/analysis/top_level_declaration.dart b/pkg/analyzer/lib/src/dart/analysis/top_level_declaration.dart
index 1ec5d068c3d7d21920f4017a3f349692f6e66106..20f5fc18cae39d0a199500226d94f76f9a29a55f 100644
--- a/pkg/analyzer/lib/src/dart/analysis/top_level_declaration.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/top_level_declaration.dart
@@ -12,28 +12,34 @@ class TopLevelDeclaration {
   final String name;
 
   TopLevelDeclaration(this.kind, this.name);
-}
 
-/**
- * Kind of a top-level declaration.
- *
- * We don't need it to be precise, just enough to support quick fixes.
- */
-enum TopLevelDeclarationKind { type, function, variable }
+  @override
+  String toString() => '($kind, $name)';
+}
 
 /**
- * Top-level declarations in the export namespace of a library.
+ * A declaration in a source.
  */
-class TopLevelLibraryDeclarations {
+class TopLevelDeclarationInSource {
   /**
-   * The source of the library.
+   * The declaring source.
    */
   final Source source;
 
   /**
-   * Top-level declarations in the export namespace of the library.
+   * The declaration.
    */
-  final List<TopLevelDeclaration> declarations = [];
+  final TopLevelDeclaration declaration;
 
-  TopLevelLibraryDeclarations(this.source);
+  TopLevelDeclarationInSource(this.source, this.declaration);
+
+  @override
+  String toString() => '($source, $declaration)';
 }
+
+/**
+ * Kind of a top-level declaration.
+ *
+ * We don't need it to be precise, just enough to support quick fixes.
+ */
+enum TopLevelDeclarationKind { type, function, variable }