dart2js cps: Clean up and avoid processing unreachable code.

pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart

Index: pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart
diff --git a/pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart b/pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart
index d6f798fbe685fec9ba70170e843b45345617b812..84c5200515ff58d2f8c9d1082a5874ac7c05177c 100644
--- a/pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart
+++ b/pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart
@@ -500,11 +500,6 @@ class Builder implements cps_ir.Visitor/*<NodeCallback|Node>*/ {
     return createInnerBuilder().buildFunction(function);
   }
 
-  Expression visitCreateFunction(cps_ir.CreateFunction node) {
-    FunctionDefinition def = makeSubFunction(node.definition);
-    return new FunctionExpression(def);
-  }
-
   Expression visitReifyRuntimeType(cps_ir.ReifyRuntimeType node) {
     return new ReifyRuntimeType(
         getVariableUse(node.value), node.sourceInformation);