cps-ir: Don't bail on assert in unchecked mode.

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 8909912d34273ae6d77a54eb5a07a31ac550c6c8..b57f0bacf19fed22909cfc85a9d36d894582b489 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
@@ -636,12 +636,12 @@ abstract class IrBuilderVisitor extends ast.Visitor<ir.Primitive>
 
   // ## Sends ##
   @override
-  ir.Primitive visitAssert(
-      ast.Send node,
-      ast.Node condition,
-      _) {
+  visitAssert(ast.Send node, ast.Node condition, _) {

[karlklose, 2015/04/13 12:31:51]

I would prefer to keep the type annotation and to structure the code like this:

  if (compiler.enableUserAssertions) {
    return giveup(node, 'assert in checked mode not implemented');
  } else {
    // The call to assert and its argument expression can be ignored
    // in production mode.
    return null;
  }

[asgerf, 2015/04/13 12:35:55]

Done.

     assert(irBuilder.isOpen);
-    return giveup(node, 'Assert');
+    if (!compiler.enableUserAssertions) {
+      return;
+    }
+    giveup(node, 'Assert');
   }
 
   ir.Primitive visitNamedArgument(ast.NamedArgument node) {