Remove some warnings and dead code in dart2js.

lib/compiler/implementation/ssa/optimize.dart

Index: lib/compiler/implementation/ssa/optimize.dart
diff --git a/lib/compiler/implementation/ssa/optimize.dart b/lib/compiler/implementation/ssa/optimize.dart
index 63777d8ed0e8fa93181bdf16fb158f511c9bae69..44f876d806c5c6e18492c99ad109574164e5fc20 100644
--- a/lib/compiler/implementation/ssa/optimize.dart
+++ b/lib/compiler/implementation/ssa/optimize.dart
@@ -247,7 +247,7 @@ class SsaConstantFolder extends HBaseVisitor implements OptimizationPhase {
   }
 
   bool isFixedSizeListConstructor(HInvokeStatic node) {
-    Element element = node.inputs[0].element;
+    Element element = node.target.element;
     DartType defaultClass = compiler.listClass.defaultClass;
     // TODO(ngeoffray): make sure that the only reason the List class is
     // not resolved is because it's not being used.