Start creating a MemberSet abstraction, and use it to fold getters/setters into field accesses.

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 535 matching lines @@
     return node;
   }
 
   HInstruction visitTypeConversion(HTypeConversion node) {
     HInstruction value = node.inputs[0];
     // If the union of the types is still the input type then
     // no conversion is required.
     HType combinedType = value.propagatedType.union(node.propagatedType);
     return (combinedType == value.propagatedType) ? value : node;
   }
+
+  HInstruction visitInvokeDynamicGetter(HInvokeDynamicGetter node) {
+    HInstruction receiver = node.inputs[0];
+    if (!receiver.propagatedType.isUseful()) return node;
+    Type type = receiver.propagatedType.computeType(compiler);
+    if (type === null) return node;
+    if (!compiler.world.isOnlyFields(type, node.name)) return node;
+    return new HFieldGet(node.name, node.inputs[0]);
+  }
+
+  HInstruction visitInvokeDynamicSetter(HInvokeDynamicSetter node) {
+    HInstruction receiver = node.inputs[0];
+    if (!receiver.propagatedType.isUseful()) return node;
+    Type type = receiver.propagatedType.computeType(compiler);
+    if (type === null) return node;
+    if (!compiler.world.isOnlyFields(type, node.name)) return node;
+    return new HFieldSet(node.name, node.inputs[0], node.inputs[1]);
+  }
 }
 
 class SsaCheckInserter extends HBaseVisitor implements OptimizationPhase {
   final String name = "SsaCheckInserter";
   Element lengthInterceptor;
 
   SsaCheckInserter(Compiler compiler) {
     SourceString lengthString = const SourceString('length');
     lengthInterceptor =
         compiler.builder.interceptors.getStaticGetInterceptor(lengthString);
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         // 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.
     }
   }
 }