Implement modular compilation

lib/src/codegen/js_interop.dart

-// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-import 'package:analyzer/dart/ast/ast.dart';
-import 'package:analyzer/src/generated/constant.dart';
-import 'package:analyzer/dart/element/element.dart';
-import 'package:analyzer/src/generated/resolver.dart' show TypeProvider;
-
-import '../utils.dart';
-
-bool _isJsLibType(String expectedName, Element e) =>
-    e?.name == expectedName && _isJsLib(e.library);
-
-/// Returns true if [e] represents any library from `package:js` or is the
-/// internal `dart:_js_helper` library.
-bool _isJsLib(LibraryElement e) {
-  if (e == null) return false;
-  var uri = e.source.uri;
-  if (uri.scheme == 'package' && uri.path.startsWith('js/')) return true;
-  if (uri.scheme == 'dart') {
-    return uri.path == '_js_helper' || uri.path == '_foreign_helper';
-  }
-  return false;
-}
-
-/// Whether [value] is a `@rest` annotation (to be used on function parameters
-/// to have them compiled as `...` rest params in ES6 outputs).
-bool isJsRestAnnotation(DartObjectImpl value) =>
-    _isJsLibType('_Rest', value.type.element);
-
-/// Whether [i] is a `spread` invocation (to be used on function arguments
-/// to have them compiled as `...` spread args in ES6 outputs).
-bool isJsSpreadInvocation(MethodInvocation i) =>
-    _isJsLibType('spread', i.methodName?.bestElement);
-
-// TODO(jmesserly): Move JsPeerInterface to package:js (see issue #135).
-bool isJSAnnotation(DartObjectImpl value) =>
-    _isJsLibType('JS', value.type.element);
-
-bool _isBuiltinAnnotation(
-    DartObjectImpl value, String libraryName, String annotationName) {
-  var e = value?.type?.element;
-  if (e?.name != annotationName) return false;
-  var uri = e.source.uri;
-  var path = uri.pathSegments[0];
-  return uri.scheme == 'dart' && path == libraryName;
-}
-
-/// Whether [value] is a `@JSExportName` (internal annotation used in SDK
-/// instead of `@JS` from `package:js`).
-bool isJSExportNameAnnotation(DartObjectImpl value) =>
-    _isBuiltinAnnotation(value, '_foreign_helper', 'JSExportName');
-
-bool isJsName(DartObjectImpl value) =>
-    _isBuiltinAnnotation(value, '_js_helper', 'JSName');
-
-bool isJsPeerInterface(DartObjectImpl value) =>
-    _isBuiltinAnnotation(value, '_js_helper', 'JsPeerInterface');
-
-bool isNativeAnnotation(DartObjectImpl value) =>
-    _isBuiltinAnnotation(value, '_js_helper', 'Native');
-
-/// Returns the name value of the `JSExportName` annotation (when compiling
-/// the SDK), or `null` if there's none. This is used to control the name
-/// under which functions are compiled and exported.
-String getJSExportName(Element e, TypeProvider types) {
-  if (!e.source.isInSystemLibrary) {
-    return null;
-  }
-  var jsName = findAnnotation(e, isJSExportNameAnnotation);
-  return getConstantField(jsName, 'name', types.stringType)?.toStringValue();
-}