Fix loop-invariant code motion.

lib/compiler/implementation/ssa/optimize.dart

 // Copyright (c) 2012, 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 868 matching lines @@
           }
         }
 
         // If the inputs are loop invariant, we can move the
         // instruction from the current block to the pre-header block.
         if (loopInvariantInputs) {
           block.detach(instruction);
           preheader.moveAtExit(instruction);
         }
       }
+      int oldChangesFlags = changesFlags;
+      changesFlags |= instruction.getChangesFlags();
+      if (oldChangesFlags != changesFlags) {
+        dependsFlags = HInstruction.computeDependsOnFlags(changesFlags);
+      }
       instruction = next;
     }
   }
 
   bool isInputDefinedAfterDominator(HInstruction input,
                                     HBasicBlock dominator) {
     return input.block.id > dominator.id;
   }
 
   void visitBasicBlock(HBasicBlock block, ValueSet values) {
@@ skipping 402 matching lines @@
       // this type for the field is still a strong signal
       // indicating the expected type of the field.
       field.propagatedType = type;
     } else {
       // If there are no invoked setters we know the type of
       // this field for sure.
       field.guaranteedType = type;
     }
   }
 }