enable top-level @JS() getters

lib/src/compiler/code_generator.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 'dart:collection' show HashMap, HashSet;
 import 'dart:math' show min, max;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart' show Token, TokenType;
@@ skipping 2307 matching lines @@
       if (jsArgs != null) {
         var genericName = _emitTopLevelName(element, suffix: '\$');
         return js.call('#(#)', [genericName, jsArgs]);
       }
     }
 
     return _emitTopLevelName(element);
   }
 
   JS.PropertyAccess _emitTopLevelName(Element e, {String suffix: ''}) {
+    if (e is TopLevelVariableElement &&
+        e.getter != null &&
+        findAnnotation(e.getter, isPublicJSAnnotation) != null) {
+      var annotationName = getAnnotationName(e.getter, isPublicJSAnnotation);
+      var name = js.string(annotationName ?? e.name);
+      return new JS.PropertyAccess(new JS.Identifier('self'), name);

[Jennifer Messerly, 2016/05/13 23:19:17]

Where is "self" coming from?

[Harry Terkelsen, 2016/05/13 23:34:43]

hmm, I've mostly been doing it because dart2js uses self. It is working with the
tests because 'window.self = this' but we'd probably run into issues if someone
set 'self' in a method. Is there a DDC way to refer to the 'window' object in a
way that will never get overwritten?

[Jennifer Messerly, 2016/05/13 23:51:07]

Hmmmmm ... I don't think we have a reliable way to reach "window". Using "this"
at the top level scope should do it. You could inject a temporary: `const self =
this;` at the module level to provide access.
http://www.ecma-international.org/ecma-262/6.0/#sec-global-environment-records

(That said I'm not 100% sure if our ES5 module transform won't mess that pattern
up, but conceptually I think it works :) )

[Harry Terkelsen, 2016/05/16 16:18:13]

Done.

+    }
     String name = getJSExportName(e) + suffix;
     return new JS.PropertyAccess(
         emitLibraryName(e.library), _propertyName(name));
   }
 
   @override
   JS.Expression visitAssignmentExpression(AssignmentExpression node) {
     var left = node.leftHandSide;
     var right = node.rightHandSide;
     if (node.operator.type == TokenType.EQ) return _emitSet(left, right);
@@ skipping 193 matching lines @@
             [jsTarget, new JS.ArrayInitializer(typeArgs), memberName, args]);
       } else {
         return js.call('dart.dsend(#, #, #)', [jsTarget, memberName, args]);
       }
     }
     if (_isObjectMemberCall(target, name)) {
       assert(typeArgs == null); // Object methods don't take type args.
       return js.call('dart.#(#, #)', [name, jsTarget, args]);
     }
 
-    jsTarget = new JS.PropertyAccess(jsTarget, memberName);
-
-    if (typeArgs != null) jsTarget = new JS.Call(jsTarget, typeArgs);
-
     if (DynamicInvoke.get(node.methodName)) {
       // This is a dynamic call to a statically known target. For example:
       //     class Foo { Function bar; }
       //     new Foo().bar(); // dynamic call
-      return js.call('dart.dcall(#, #)', [jsTarget, args]);
+      if (typeArgs != null) {

[Jennifer Messerly, 2016/05/13 23:19:16]

just curious about the reason for this change?

Overall I think it's a good idea :) -- the "dynamic call to a static target"
case was a bit flaky. But just curious what particular case you hit.

[Harry Terkelsen, 2016/05/13 23:34:43]

Basically because of this line:
https://github.com/dart-lang/dev_compiler/blob/master/test/codegen/lib/html/j...

[Jennifer Messerly, 2016/05/13 23:51:06]

Thanks, makes sense :)

+        return js.call('dart.dgsend(#, #, #, #)',

[Jennifer Messerly, 2016/05/13 23:19:17]

this code looks copy+pasted, can we share it with _emitMethodCall somehow?

[Harry Terkelsen, 2016/05/13 23:34:43]

I merged it with the above

[Jennifer Messerly, 2016/05/13 23:51:06]

Looks great :)

+            [jsTarget, new JS.ArrayInitializer(typeArgs), memberName, args]);
+      } else {
+        return js.call('dart.dsend(#, #, #)', [jsTarget, memberName, args]);
+      }
     }
 
+    jsTarget = new JS.PropertyAccess(jsTarget, memberName);
+    if (typeArgs != null) jsTarget = new JS.Call(jsTarget, typeArgs);
+
     return new JS.Call(jsTarget, args);
   }
 
   /// Emits a function call, to a top-level function, local function, or
   /// an expression.
   JS.Expression _emitFunctionCall(InvocationExpression node) {
     var fn = _visit(node.function);
     var args = _visit(node.argumentList);
     if (DynamicInvoke.get(node.function)) {
       var typeArgs = _emitInvokeTypeArguments(node);
@@ skipping 1902 matching lines @@
 }
 
 bool isLibraryPrefix(Expression node) =>
     node is SimpleIdentifier && node.staticElement is PrefixElement;
 
 LibraryElement _getLibrary(AnalysisContext c, String uri) =>
     c.computeLibraryElement(c.sourceFactory.forUri(uri));
 
 bool _isDartRuntime(LibraryElement l) =>
     l.isInSdk && l.source.uri.toString() == 'dart:_runtime';