Fix dart.registerExtension

Author: Olivier Chafik

lib/runtime/dart/_interceptors.js

@@ -393,7 +393,6 @@ dart_library.library('dart/_interceptors', null, /* Imports */[
       }
     }
     dart.setBaseClass(JSArray, dart.global.Array);
-    dart.registerExtension(dart.global.Array, JSArray);
     JSArray[dart.implements] = () => [core.List$(E), JSIndexable];
     dart.setSignature(JSArray, {
       constructors: () => ({
@@ -456,6 +455,7 @@ dart_library.library('dart/_interceptors', null, /* Imports */[
     return JSArray;
   });
   let JSArray = JSArray$();
+  dart.registerExtension(dart.global.Array, JSArray);
   let JSMutableArray$ = dart.generic(function(E) {
     class JSMutableArray extends JSArray$(E) {
       JSMutableArray() {
@@ -956,7 +956,6 @@ dart_library.library('dart/_interceptors', null, /* Imports */[
       return dart.as(~this >>> 0, core.int);
     }
   }
-  dart.registerExtension(dart.global.Number, JSInt);
   JSInt[dart.implements] = () => [core.int, core.double];
   dart.setSignature(JSInt, {
     constructors: () => ({JSInt: [JSInt, []]}),
@@ -975,6 +974,7 @@ dart_library.library('dart/_interceptors', null, /* Imports */[
     names: ['_bitCount', '_shru', '_shrs', '_ors', '_spread']
   });
   JSInt[dart.metadata] = () => [dart.const(new _js_helper.JsPeerInterface({name: 'Number'}))];
+  dart.registerExtension(dart.global.Number, JSInt);
   dart.defineExtensionNames([
     'runtimeType'
   ]);
@@ -1450,7 +1450,6 @@ dart_library.library('dart/_interceptors', null, /* Imports */[
       return this[index];
     }
   }
-  dart.registerExtension(dart.global.String, JSString);
   JSString[dart.implements] = () => [core.String, JSIndexable];
   dart.setSignature(JSString, {
     constructors: () => ({JSString: [JSString, []]}),
@@ -1490,6 +1489,7 @@ dart_library.library('dart/_interceptors', null, /* Imports */[
     names: ['_isWhitespace', '_skipLeadingWhitespace', '_skipTrailingWhitespace']
   });
   JSString[dart.metadata] = () => [dart.const(new _js_helper.JsPeerInterface({name: 'String'}))];
+  dart.registerExtension(dart.global.String, JSString);
   let _string = Symbol('_string');
   class _CodeUnits extends _internal.UnmodifiableListBase$(core.int) {
     _CodeUnits(string) {
@@ -1530,12 +1530,12 @@ dart_library.library('dart/_interceptors', null, /* Imports */[
       return core.bool;
     }
   }
-  dart.registerExtension(dart.global.Boolean, JSBool);
   JSBool[dart.implements] = () => [core.bool];
   dart.setSignature(JSBool, {
     constructors: () => ({JSBool: [JSBool, []]})
   });
   JSBool[dart.metadata] = () => [dart.const(new _js_helper.JsPeerInterface({name: 'Boolean'}))];
+  dart.registerExtension(dart.global.Boolean, JSBool);
   class JSIndexable extends core.Object {}
   class JSMutableIndexable extends JSIndexable {}
   class JSObject extends core.Object {}

lib/src/codegen/js_codegen.dart

@@ -65,10 +65,16 @@ class _ClassBuilder {
   final List<JS.Statement> prelude = [];
   /// Members of the class declaration.
   final List<JS.Method> body = [];
-  /// Builders for statements that should appear after the class declaration.
-  /// These builders will get a qualified reference to the class as argument so
-  /// they can refer to it if they so wish.
+  /// Builders for statements that should appear just after the class
+  /// declaration. These builders will get a local or qualified reference to the
+  /// class as argument so they can refer to it if they so wish.
+  ///
+  /// Note that these statements may be wrapped in generic or lazy classes
+  /// definitions, so they might not be top-level.
   final List<_ClassRefStatementBuilder> statements = [];
+  /// Statements for extension classes are treated separately, as they need to
+  /// be at the top-level.
+  final List<JS.Statement> topLevelStatements = [];
 
   _ClassBuilder(this.info);
 }
@@ -653,7 +659,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
         new JS.Identifier(name),
         heritage,
         builder.body.where((m) => m != null).toList(growable: false));
-    return _finishType(element.type, ({bool isExportable}) {
+    var result = _finishType(element.type, ({bool isExportable}) {
       var classRef = isExportable
           ? _maybeQualifiedLocalType(name)
           : new JS.Identifier(name);
@@ -665,6 +671,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
             return statementBuilder(classRef);
           })));
     });
+    return _statement([result]..addAll(builder.topLevelStatements));
   }
 
   /// Given a class definition statement factory, completes its declaration.
@@ -805,11 +812,11 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
     // Probably fine for objects coming from JS, but not if we actually
     // want to support construction of instances with generic types other
     // than dynamic. See issue #154 for Array and List<E> related bug.
-    builder.statements.add((classRef) =>
+    builder.topLevelStatements.add(
         js.statement(
           'dart.registerExtension(dart.global.#, #);', [
               _propertyName(jsPeerName),
-              classRef
+              classElem.name
           ]));
   }
   void _addClassInterfaces(_ClassBuilder builder) {