[kernel] Delete most of the AST

pkg/kernel/lib/ast.dart

Index: pkg/kernel/lib/ast.dart
diff --git a/pkg/kernel/lib/ast.dart b/pkg/kernel/lib/ast.dart
index dcc0285ef761ae0f0e3c3e146f4b52626fbc384f..df81e611475f24c298880bb0367d65e5dd973bc9 100644
--- a/pkg/kernel/lib/ast.dart
+++ b/pkg/kernel/lib/ast.dart
@@ -242,6 +242,9 @@ class Reference {
 // ------------------------------------------------------------------------
 
 class Library extends NamedNode implements Comparable<Library> {
+  /// Offset of the declaration, set and used when writing the binary.
+  int binaryOffset = -1;
+
   /// An import path to this library.
   ///
   /// The [Uri] should have the `dart`, `package`, `app`, or `file` scheme.