Generate tear-off closures dynamically.

dart/sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart

Index: dart/sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart b/dart/sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart
index eabc1d1a8c61e0dd1631522a4459587d5d0f773a..9d9a89b3d2d6f10006559f594d83367db75f683e 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart
@@ -108,7 +108,6 @@ class ClassEmitter extends CodeEmitterHelper {
       throw new SpannableAssertionFailure(
           element, 'Must be a ClassElement or a LibraryElement');
     }
-    StringBuffer buffer = new StringBuffer();
     if (emitStatics) {
       assert(invariant(element, superName == null, message: superName));
     } else {
@@ -116,16 +115,13 @@ class ClassEmitter extends CodeEmitterHelper {
       String nativeName =
           namer.getPrimitiveInterceptorRuntimeName(element);
       if (nativeName != null) {
-        buffer.write('$nativeName/');
+        builder.nativeName = nativeName;
       }
-      buffer.write('$superName;');
+      builder.superName = superName;
     }
-    int bufferClassLength = buffer.length;
-
-    String separator = '';
-
     var fieldMetadata = [];
     bool hasMetadata = false;
+    bool fieldsAdded = false;
 
     if (!onlyForRti) {
       visitFields(element, emitStatics,
@@ -142,8 +138,6 @@ class ClassEmitter extends CodeEmitterHelper {
         // constructors, so we don't need the fields unless we are generating
         // accessors at runtime.
         if (!classIsNative || needsAccessor) {
-          buffer.write(separator);
-          separator = ',';
           var metadata = task.metadataEmitter.buildMetadataFunction(field);
           if (metadata != null) {
             hasMetadata = true;
@@ -152,16 +146,17 @@ class ClassEmitter extends CodeEmitterHelper {
           }
           fieldMetadata.add(metadata);
           recordMangledField(field, accessorName, field.name);
+          String fieldName = name;
+          String fieldCode = '';
+          String reflectionMarker = '';
           if (!needsAccessor) {
             // Emit field for constructor generation.
             assert(!classIsNative);
-            buffer.write(name);
           } else {
             // Emit (possibly renaming) field name so we can add accessors at
             // runtime.
-            buffer.write(accessorName);
             if (name != accessorName) {
-              buffer.write(':$name');
+              fieldName = '$accessorName:$name';
             }
 
             int getterCode = 0;
@@ -208,28 +203,25 @@ class ClassEmitter extends CodeEmitterHelper {
               compiler.reportInternalError(
                   field, 'Internal error: code is 0 ($element/$field)');
             } else {
-              buffer.write(FIELD_CODE_CHARACTERS[code - FIRST_FIELD_CODE]);
+              fieldCode = FIELD_CODE_CHARACTERS[code - FIRST_FIELD_CODE];
             }
           }
           if (backend.isAccessibleByReflection(field)) {
-            buffer.write('-');
+            reflectionMarker = '-';
             if (backend.isNeededForReflection(field)) {
               DartType type = field.computeType(compiler);
-              buffer.write('${task.metadataEmitter.reifyType(type)}');
+              reflectionMarker = '-${task.metadataEmitter.reifyType(type)}';
             }
           }
+          builder.addField('$fieldName$fieldCode$reflectionMarker');
+          fieldsAdded = true;
         }
       });
     }
 
-    bool fieldsAdded = buffer.length > bufferClassLength;
-    String compactClassData = buffer.toString();
-    jsAst.Expression classDataNode = js.string(compactClassData);
     if (hasMetadata) {
-      fieldMetadata.insert(0, classDataNode);
-      classDataNode = new jsAst.ArrayInitializer.from(fieldMetadata);
+      builder.fieldMetadata = fieldMetadata;
     }
-    builder.addProperty('', classDataNode);
     return fieldsAdded;
   }
 
@@ -321,7 +313,7 @@ class ClassEmitter extends CodeEmitterHelper {
     List<jsAst.Property> statics = new List<jsAst.Property>();
     ClassBuilder staticsBuilder = new ClassBuilder();
     if (emitFields(classElement, staticsBuilder, null, emitStatics: true)) {
-      statics.add(staticsBuilder.properties.single);
+      statics.add(staticsBuilder.toObjectInitializer().properties.single);
     }
 
     Map<String, ClassBuilder> classPropertyLists =