dart2js: add compiler builtins to the core-runtime.

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

Index: pkg/compiler/lib/src/js_emitter/old_emitter/setup_program_builder.dart
diff --git a/pkg/compiler/lib/src/js_emitter/old_emitter/setup_program_builder.dart b/pkg/compiler/lib/src/js_emitter/old_emitter/setup_program_builder.dart
index 5d77ebdc207b547a937db49569d2d7e5689d82cc..58ad5bd8f634c6c66846aec8214d90cb4ade494b 100644
--- a/pkg/compiler/lib/src/js_emitter/old_emitter/setup_program_builder.dart
+++ b/pkg/compiler/lib/src/js_emitter/old_emitter/setup_program_builder.dart
@@ -21,8 +21,10 @@ const RANGE2_ADJUST = - (FIRST_FIELD_CODE + RANGE1_SIZE - RANGE2_FIRST);
 const RANGE3_ADJUST =
     - (FIRST_FIELD_CODE + RANGE1_SIZE + RANGE2_SIZE - RANGE3_FIRST);
 
-String get setupProgramName => 'setupProgram';
-
+const String setupProgramName ='setupProgram';
+// TODO(floitsch): make sure this property can't clash with anything. It's
+//   unlikely since it lives on types, but still.
+const String typeNameProperty = r'builtin$cls';
 
 jsAst.Statement buildSetupProgram(Program program, Compiler compiler,
                                 JavaScriptBackend backend,
@@ -237,7 +239,7 @@ function $setupProgramName(programData, typesOffset) {
         body += "this." + #deferredActionString + "();";
       }
       str += ") {\\n" + body + "}\\n";
-      str += name + ".builtin\$cls=\\"" + name + "\\";\\n";
+      str += name + ".$typeNameProperty=\\"" + name + "\\";\\n";
       str += "\$desc=\$collectedClasses." + name + "[1];\\n";
       str += name + ".prototype = \$desc;\\n";
       if (typeof defineClass.name != "string") {