Fasta type inference prototype #2

pkg/front_end/lib/src/fasta/builder/ast_factory.dart

+import 'package:kernel/ast.dart' show DartType, TreeNode;
+import 'shadow_ast.dart';
+
+abstract class AstFactory {
+  Block block(List<Statement> statements, int charOffset);
+
+  IntLiteral intLiteral(value, int charOffset);
+
+  Statement returnStatement(Expression expression, int charOffset);
+
+  VariableDeclaration variableDeclaration(String name,
+      {DartType type,
+      Expression initializer,
+      int charOffset: TreeNode.noOffset,
+      bool isFinal: false,
+      bool isConst: false});
+
+  ListLiteral listLiteral(List<Expression> expressions, DartType typeArgument,
+      bool isConst, int charOffset);
+
+  NullLiteral nullLiteral(int charOffset);
+}