dart2js cps: Handle type variables in factory constructors.

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

Index: pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart
index e768e3c154fb4a360fa86d4107f252acbaad1b38..1ab44e7146e0fd59f4417f5c15b9484bb12c4b25 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_builder_task.dart
@@ -192,8 +192,15 @@ abstract class IrBuilderVisitor extends ast.Visitor<ir.Primitive>
   ir.FunctionDefinition _makeFunctionBody(FunctionElement element,
                                           ast.FunctionExpression node) {
     FunctionSignature signature = element.functionSignature;
-    List<ParameterElement> parameters = [];
-    signature.orderedForEachParameter(parameters.add);
+    List<Local> parameters = <Local>[];
+    signature.orderedForEachParameter((e) => parameters.add(e));
+
+    if (element.isFactoryConstructor) {
+      // Type arguments are passed in as extra parameters.
+      for (DartType typeVariable in element.enclosingClass.typeVariables) {
+        parameters.add(new TypeVariableLocal(typeVariable, element));
+      }
+    }
 
     irBuilder.buildFunctionHeader(parameters,
                                   closureScope: getClosureScopeForNode(node),