Fix regression on constant folding an interceptor into a dynamic invocation.

lib/compiler/implementation/ssa/optimize.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 interface OptimizationPhase {
   String get name();
   void visitGraph(HGraph graph);
 }
 
 class SsaOptimizerTask extends CompilerTask {
@@ skipping 167 matching lines @@
         MapConstant constant = constantInput.constant;
         return graph.addConstantInt(constant.length);
       }
     }
 
     if (input.isString()
         && node.name == const SourceString('toString')) {
       return node.inputs[1];
     }
 
-    if (!input.canBePrimitive() && !node.getter) {
+    if (!input.canBePrimitive() && !node.getter && !node.setter) {
       return fromInterceptorToDynamicInvocation(node, node.name);
     }
 
     return node;
   }
 
   HInstruction visitInvokeDynamic(HInvokeDynamic node) {
     HType receiverType = node.receiver.propagatedType;
     if (receiverType.isExact()) {
       HExactType type = receiverType;
@@ skipping 380 matching lines @@
   }
 
   HBoundsCheck insertBoundsCheck(HInstruction node,
                                  HInstruction receiver,
                                  HInstruction index) {
     HStatic interceptor = new HStatic(lengthInterceptor);
     node.block.addBefore(node, interceptor);
     HInvokeInterceptor length = new HInvokeInterceptor(
         Selector.INVOCATION_0,
         const SourceString("length"),
-        true,
-        <HInstruction>[interceptor, receiver]);
+        <HInstruction>[interceptor, receiver],
+        getter: true);
     length.propagatedType = HType.INTEGER;
     node.block.addBefore(node, length);
 
     HBoundsCheck check = new HBoundsCheck(length, index);
     node.block.addBefore(node, check);
     return check;
   }
 
   HIntegerCheck insertIntegerCheck(HInstruction node, HInstruction value) {
     HIntegerCheck check = new HIntegerCheck(value);
@@ skipping 487 matching lines @@
         // the if block terminates. So any use of the instruction
         // after the join block should be changed to the new
         // instruction.
         changeUsesDominatedBy(ifUser.joinBlock, input, convertedType);
       }
       // TODO(ngeoffray): Also change uses for the then block on a HType
       // that knows it is not of a specific Type.
     }
   }
 }