tree-ir: Do not merge captured parameters with other variables.

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 3f2d1331409f1e097ed6d373ab28e3edbeac41b9..0683911c095fc46bf697f617d93745040fc4257f 100644
--- a/pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart
+++ b/pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart
@@ -156,7 +156,8 @@ class Builder implements cps_ir.Visitor<Node> {
     if (variable is cps_ir.Parameter) {
       return getVariable(variable);
     } else {
-      return addMutableVariable(variable as cps_ir.MutableVariable);
+      return addMutableVariable(variable as cps_ir.MutableVariable)
+              ..isCaptured = true;

[asgerf, 2015/04/15 10:43:39]

This is for parameters accessed by initializers.

     }
   }