Mark the local for this as used if a constructor call needs type variables.

lib/compiler/implementation/closure.dart

Index: lib/compiler/implementation/closure.dart
diff --git a/lib/compiler/implementation/closure.dart b/lib/compiler/implementation/closure.dart
index f278e6ba8ba7b5118f37e1dcb0d93a0f15ef6f9b..bfa29101e403d21265a14fdc2039f775497cf871 100644
--- a/lib/compiler/implementation/closure.dart
+++ b/lib/compiler/implementation/closure.dart
@@ -317,6 +317,30 @@ class ClosureTranslator extends AbstractVisitor {
     super.visitSendSet(node);
   }
 
+  visitNewExpression(NewExpression node) {
+    bool hasTypeVariable(DartType type) {
+      if (type is TypeVariableType) {
+        return true;
+      } else if (type is InterfaceType) {
+        InterfaceType ifcType = type;
+        for (DartType argument in ifcType.arguments) {
+          if (hasTypeVariable(argument)) {
+            return true;
+          }
+        }
+      }
+      return false;
+    }
+    TypeAnnotation annotation = node.send.getTypeAnnotation();
+    DartType type = elements.getType(annotation);
+    if (hasTypeVariable(type)) {
+      if (closureData.thisElement !== null) {

[floitsch, 2012/09/03 14:04:15]

Add comment why this is necessary. Maybe find a more direct way of testing it?
for example: closureData.isInsideInstanceMethod

+        useLocal(closureData.thisElement);
+      }
+    }
+    node.visitChildren(this);
+  }
+
   // If variables that are declared in the [node] scope are captured and need
   // to be boxed create a box-element and update the [capturingScopes] in the
   // current [closureData].