Make field-get/set work without elements.

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 574 matching lines @@
               work.element);
           break;
         case Compiler.PHASE_RECOMPILING:
           // If field is not final or const but no setters are used then the
           // field might be considered final anyway as it will be either
           // un-initialized or initialized in the constructor initializer list.
           isFinalOrConst = true;
           break;
       }
     }
-    return new HFieldGet(field, node.inputs[0], isFinalOrConst: isFinalOrConst);
+    return new HFieldGet.withElement(
+        field, node.inputs[0], isFinalOrConst: isFinalOrConst);
   }
 
   HInstruction visitInvokeDynamicSetter(HInvokeDynamicSetter node) {
     HInstruction receiver = node.inputs[0];
     if (!receiver.propagatedType.isUseful()) return node;
     if (receiver.propagatedType.canBeNull()) return node;
     Type type = receiver.propagatedType.computeType(compiler);
     if (type === null) return node;
     Element field = compiler.world.locateSingleField(type, node.name);
     if (field === null) return node;
-    return new HFieldSet(field, node.inputs[0], node.inputs[1]);
+    return new HFieldSet.withElement(field, node.inputs[0], node.inputs[1]);
   }
 
   HInstruction visitStringConcat(HStringConcat node) {
     DartString folded = const LiteralDartString("");
     for (int i = 0; i < node.inputs.length; i++) {
       HInstruction part = node.inputs[i];
       if (!part.isConstant()) return node;
       HConstant constant = part;
       if (!constant.constant.isPrimitive()) return node;
       PrimitiveConstant primitive = constant.constant;
@@ skipping 685 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;
     }
   }
 }