Force slow objects for select objects during startup.

pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart

Index: pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart b/pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart
index 9d5be9da87f9d2fcd7221bb7c1c31535c25d9b32..a7b3e56d88b01d8ab2c303cc5b62afdb43d9b4ca 100644
--- a/pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart
@@ -331,14 +331,13 @@ class OldEmitter implements Emitter {
 
             var field = generateAccessor(fields[i], accessors, name);
             if (#hasIsolateSupport) { fieldNames += "'" + field + "',"; }
-            var parameter = "parameter_" + field;
+            var parameter = "p_" + field;
             str += parameter;
             body += ("this." + field + " = " + parameter + ";\n");
           }
           str += ") {\n" + body + "}\n";
           str += name + ".builtin$cls=\"" + name + "\";\n";
-          str += "$desc=$collectedClasses." + name + ";\n";
-          str += "if($desc instanceof Array) $desc = \$desc[1];\n";
+          str += "$desc=$collectedClasses." + name + "[1];\n";
           str += name + ".prototype = $desc;\n";
           if (typeof defineClass.name != "string") {
             str += name + ".name=\"" + name + "\";\n";
@@ -426,6 +425,7 @@ class OldEmitter implements Emitter {
           return function (constructor, superConstructor) {
             tmp.prototype = superConstructor.prototype;
             var object = new tmp();
+            object.x = 0; delete object.x; // Make object slow.

[floitsch, 2015/02/24 20:21:39]

I discussed and benchmarked this with Slava. It looks like setting the __proto__
is a good option.
Short term this is the easier fix, though.

[herhut, 2015/03/09 15:11:05]

Acknowledged.

             var properties = constructor.prototype;
             var members = Object.keys(properties);
             for (var i = 0; i < members.length; i++) {