dart2js cps: Handle optional parameters in builder.

pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart

Index: pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart
index f883b9b9c38613e28b17b3cb0461338efe93a294..61a3b529acc6c4f969bb23781a2c40fe76b90f05 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart
@@ -731,14 +731,6 @@ abstract class IrBuilder {
         (k) => new ir.ConcatenateStrings(k, arguments));
   }
 
-  /// Create an invocation of [local] where the argument structure is defined
-  /// by [selector] and the argument values are defined by [arguments].
-  ir.Primitive buildLocalInvocation(LocalElement local,
-                                    Selector selector,
-                                    List<ir.Definition> arguments) {
-    return _buildInvokeCall(buildLocalGet(local), selector, arguments);
-  }
-
   /// Create an invocation of the [functionExpression] where the argument
   /// structure are defined by [selector] and the argument values are defined by
   /// [arguments].