Create and use new change/depends flags for the GVN analysis.

lib/compiler/implementation/ssa/builder.dart

Index: lib/compiler/implementation/ssa/builder.dart
===================================================================
--- lib/compiler/implementation/ssa/builder.dart	(revision 13049)
+++ lib/compiler/implementation/ssa/builder.dart	(working copy)
@@ -2181,14 +2181,16 @@
     if (methodInterceptionEnabled) {
       staticInterceptor = interceptors.getStaticSetInterceptor(setterName);
     }
+    bool hasSetter = compiler.world.hasAnyUserDefinedSetter(selector);
     if (staticInterceptor != null) {
       HStatic target = new HStatic(staticInterceptor);
       add(target);
       List<HInstruction> inputs = <HInstruction>[target, receiver, value];
       addWithPosition(new HInvokeInterceptor(selector, inputs), send);
     } else {
-      addWithPosition(new HInvokeDynamicSetter(selector, null, receiver, value),
-                      send);
+      addWithPosition(
+          new HInvokeDynamicSetter(selector, null, receiver, value, !hasSetter),
+          send);
     }
     stack.add(value);
   }