cleans up sdk patching so we no longer have unresolved names

lib/src/codegen/js_codegen.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.
 
 library ddc.src.codegen.js_codegen;
 
 import 'dart:io' show Directory, File;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/src/generated/ast.dart' hide ConstantEvaluator;
@@ skipping 306 matching lines @@
 
     var body = _initializeFields(fields);
     var superCall = _superConstructorCall(node);
     if (superCall != null) body = [[body, superCall]];
     return new JS.Method(
         new JS.PropertyName(name), js.call('function() { #; }', body));
   }
 
   JS.Method _emitConstructor(ConstructorDeclaration node, String className,
       List<FieldDeclaration> fields) {
-    if (node.externalKeyword != null) return null;
+    if (_externalOrNative(node)) return null;
 
     var name = _constructorName(className, node.name);
 
     // We generate constructors as initializer methods in the class;
     // this allows use of `super` for instance methods/properties.
     // It also avoids V8 restrictions on `super` in default constructors.
     return new JS.Method(new JS.PropertyName(name), new JS.Fun(
         node.parameters.accept(this), _emitConstructorBody(node, fields)));
   }
 
@@ skipping 195 matching lines @@
   JS.Expression _defaultParamValue(FormalParameter param) {
     if (param is DefaultFormalParameter && param.defaultValue != null) {
       return param.defaultValue.accept(this);
     } else {
       return new JS.LiteralNull();
     }
   }
 
   @override
   JS.Method visitMethodDeclaration(MethodDeclaration node) {
-    if (node.isAbstract || node.externalKeyword != null) return null;
+    if (node.isAbstract || _externalOrNative(node)) {
+      return null;
+    }
 
     var params = _visit(node.parameters);
     if (params == null) params = [];
 
     return new JS.Method(new JS.PropertyName(_jsMethodName(node.name.name)),
         new JS.Fun(params, node.body.accept(this)),
         isGetter: node.isGetter,
         isSetter: node.isSetter,
         isStatic: node.isStatic);
   }
 
   @override
   JS.Statement visitFunctionDeclaration(FunctionDeclaration node) {
     assert(node.parent is CompilationUnit);
 
-    if (node.externalKeyword != null) return null;
+    if (_externalOrNative(node)) return null;
 
     if (node.isGetter || node.isSetter) {
       // Add these later so we can use getter/setter syntax.
       _properties.add(node);
       return null;
     }
 
     var body = <JS.Statement>[];
     _flushLibraryProperties(body);
 
@@ skipping 1023 matching lines @@
   ///     x['+'](y)
   ///
   /// Equality is a bit special, it is generated via the Dart `equals` runtime
   /// helper, that checks for null. The user defined method is called '=='.
   String _jsMethodName(String name) {
     if (name == '[]') return 'get';
     if (name == '[]=') return 'set';
     return name;
   }
 
+  bool _externalOrNative(node) =>
+      node.externalKeyword != null || _functionBody(node) is NativeFunctionBody;
+
+  FunctionBody _functionBody(node) =>
+      node is FunctionDeclaration ? node.functionExpression.body : node.body;
+
   String _maybeBindThis(node) {
     if (currentClass == null) return '';
     var visitor = _BindThisVisitor._instance;
     visitor._bindThis = false;
     node.accept(visitor);
     return visitor._bindThis ? '.bind(this)' : '';
   }
 
   static bool _needsImplicitThis(Element e) =>
       e is PropertyAccessorElement && !e.variable.isStatic ||
@@ skipping 92 matching lines @@
 /// Choose a canonical name from the library element.
 /// This never uses the library's name (the identifier in the `library`
 /// declaration) as it doesn't have any meaningful rules enforced.
 String jsLibraryName(LibraryElement library) => canonicalLibraryName(library);
 
 /// Path to file that will be generated for [info].
 // TODO(jmesserly): library directory should be relative to its package
 // root. For example, "package:dev_compiler/src/codegen/js_codegen.dart" would be:
 // "ddc/src/codegen/js_codegen.js" under the output directory.
 String jsOutputPath(LibraryInfo info) => '${info.name}/${info.name}.js';