dart2js: Construct the entire output as a single AST before printing.

pkg/compiler/lib/src/js_backend/constant_emitter.dart

Index: pkg/compiler/lib/src/js_backend/constant_emitter.dart
diff --git a/pkg/compiler/lib/src/js_backend/constant_emitter.dart b/pkg/compiler/lib/src/js_backend/constant_emitter.dart
index 1b3e95fed7efa0b9fb1b0a6ff69d9d1e2ac6fc74..0d3ce4ffc976a6059fb00c6ca12ed29f1806b5a9 100644
--- a/pkg/compiler/lib/src/js_backend/constant_emitter.dart
+++ b/pkg/compiler/lib/src/js_backend/constant_emitter.dart
@@ -296,11 +296,11 @@ class ConstantEmitter
         backend.classNeedsRti(type.element)) {
       InterfaceType interface = type;
       RuntimeTypes rti = backend.rti;
-      Iterable<String> arguments = interface.typeArguments
+      Iterable<jsAst.Expression> arguments = interface.typeArguments
           .map((DartType type) =>
               rti.getTypeRepresentationWithHashes(type, (_){}));
       jsAst.Expression argumentList =
-          new jsAst.LiteralString('[${arguments.join(', ')}]');
+          new jsAst.ArrayInitializer(arguments.toList());
       return new jsAst.Call(getHelperProperty(backend.getSetRuntimeTypeInfo()),
                             [value, argumentList]);
     }