Collect getters in a FunctionSet while resolving.

lib/compiler/implementation/ssa/nodes.dart

Index: lib/compiler/implementation/ssa/nodes.dart
===================================================================
--- lib/compiler/implementation/ssa/nodes.dart	(revision 12169)
+++ lib/compiler/implementation/ssa/nodes.dart	(working copy)
@@ -797,6 +797,7 @@
   static const int TYPE_CONVERSION_TYPECODE = 28;
   static const int BAILOUT_TARGET_TYPECODE = 29;
   static const int INVOKE_STATIC_TYPECODE = 30;
+  static const int INVOKE_DYNAMIC_GETTER_TYPECODE = 31;
 
   HInstruction(this.inputs)
       : id = idCounter++,
@@ -1304,10 +1305,26 @@
 }
 
 class HInvokeDynamicGetter extends HInvokeDynamicField {
-  HInvokeDynamicGetter(selector, element, receiver)
+  final bool isSideEffectFree;
+  HInvokeDynamicGetter(
+      selector, element, receiver, this.isSideEffectFree)
     : super(selector, element,[receiver]);
   toString() => 'invoke dynamic getter: $selector';
   accept(HVisitor visitor) => visitor.visitInvokeDynamicGetter(this);
+
+  void prepareGvn(HTypeMap types) {
+    if (isSideEffectFree) {
+      setUseGvn();
+      clearAllSideEffects();
+      setDependsOnSomething();
+    } else {
+      setAllSideEffects();
+    }
+  }
+
+  int typeCode() => HInstruction.INVOKE_DYNAMIC_GETTER_TYPECODE;
+  bool typeEquals(other) => other is HInvokeDynamicGetter;
+  bool dataEquals(HInvokeDynamicGetter other) => selector == other.selector;
 }
 
 class HInvokeDynamicSetter extends HInvokeDynamicField {
@@ -1356,11 +1373,12 @@
 
 class HInvokeInterceptor extends HInvokeStatic {
   final Selector selector;
+  final bool isSideEffectFree;
 
   HInvokeInterceptor(this.selector,
                      List<HInstruction> inputs,
-                     [HType knownType = HType.UNKNOWN])
-      : super(inputs, knownType);
+                     [bool this.isSideEffectFree = false])
+      : super(inputs);
 
   toString() => 'invoke interceptor: ${element.name}';
   accept(HVisitor visitor) => visitor.visitInvokeInterceptor(this);
@@ -1416,6 +1434,10 @@
       // we don't express that type yet: a mutable array might be
       // extendable.
       if (!inputs[1].isString(types)) setDependsOnSomething();
+    } else if (isSideEffectFree) {
+      setUseGvn();
+      clearAllSideEffects();
+      setDependsOnSomething();
     } else {
       setAllSideEffects();
     }