Fix wrong optimization for private fields

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 4faa8e9e2e4ae016ee5352b71ae07b34f8c7f2fd..91e881584ac40dbaa05f56512b838fa3107795b7 100644
--- a/lib/compiler/implementation/ssa/optimize.dart
+++ b/lib/compiler/implementation/ssa/optimize.dart
@@ -563,6 +563,7 @@ class SsaConstantFolder extends HBaseVisitor implements OptimizationPhase {
     if (type === null) return node;
     Element field = compiler.world.locateSingleField(type, node.name);
     if (field === null) return node;
+    if (field.getLibrary() !== work.element.getLibrary()) return node;

[floitsch, 2012/08/15 11:59:42]

why not looking if the field is private?
There should be something like node.name.isPrivate.

[Søren Gjesse, 2012/08/15 12:50:04]

It works if the check is just !node.name.isPrivate(). However that regresses
some benchmarks as it hits broadly.

But thanks to noticing, as the check should still include the
node.name.isPrivate(), as the library check should only be done for private
fields.

[floitsch, 2012/08/15 12:56:34]

That's what I meant.

     Modifiers modifiers = field.modifiers;
     bool isFinalOrConst = false;
     if (modifiers != null) {