Address code review comments on r19350

sdk/lib/_internal/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.
 
 part of ssa;
 
 abstract class OptimizationPhase {
   String get name;
   void visitGraph(HGraph graph);
 }
@@ skipping 580 matching lines @@
   }
 
   HInstruction visitInvokeDynamicGetter(HInvokeDynamicGetter node) {
     if (node.isCallOnInterceptor) return handleInterceptorCall(node);
 
     Element field =
         findConcreteFieldForDynamicAccess(node.receiver, node.selector);
     if (field == null) return node;
 
     Modifiers modifiers = field.modifiers;
-    bool isFinalOrConst = modifiers.isFinal() || modifiers.isConst();
+    bool isAssignable = !(modifiers.isFinal() || modifiers.isConst());
     if (!compiler.resolverWorld.hasInvokedSetter(field, compiler)) {
       // If no setter is ever used for this field it is only initialized in the
       // initializer list.
-      isFinalOrConst = true;
+      isAssignable = false;
+    }
+    if (field.isNative()) {
+      // Some native fields are views of data that may be changed by operations.
+      // E.g. node.firstChild depends on parentNode.removeBefore(n1, n2).
+      // TODO(sra): Refine the effect classification so that native effects are
+      // distinct from ordinary Dart effects.
+      isAssignable = true;
     }
     HFieldGet result = new HFieldGet(
-        field, node.inputs[0], isAssignable: !isFinalOrConst);
-
-    // Some native fields are views of data that may be changed by operations.
-    // E.g. node.firstChild depends on parentNode.removeBefore(n1, n2).
-    // TODO(sra): Refine the effect classification so that native effects are
-    // distinct from ordinary Dart effects.
-    if (field.isNative()) {
-      result.setDependsOnSomething();
-    }
+        field, node.inputs[0], isAssignable: isAssignable);
 
     if (field.getEnclosingClass().isNative()) {
       result.instructionType =
           new HType.subtype(field.computeType(compiler), compiler);
     } else {
       HType type = new HType.inferredForElement(field, compiler);
       if (type.isUnknown()) {
         type = backend.optimisticFieldType(field);
         if (type != null) {
           backend.registerFieldTypesOptimization(
@@ skipping 912 matching lines @@
     HBasicBlock block = user.block;
     block.addAfter(user, interceptor);
     block.rewrite(user, interceptor);
     block.remove(user);
 
     // The interceptor will be removed in the dead code elimination
     // phase. Note that removing it here would not work because of how
     // the [visitBasicBlock] is implemented.
   }
 }