Redo "Dummy receiver optimization"

sdk/lib/_internal/compiler/implementation/js_backend/namer.dart

Index: sdk/lib/_internal/compiler/implementation/js_backend/namer.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_backend/namer.dart b/sdk/lib/_internal/compiler/implementation/js_backend/namer.dart
index 9b18a379801e74a635db5b6ebfc89936eac1f3ca..484fa2276b5a4822dd7ea8c6710c3a5d02887b9c 100644
--- a/sdk/lib/_internal/compiler/implementation/js_backend/namer.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_backend/namer.dart
@@ -1181,6 +1181,10 @@ class ConstantNamingVisitor implements ConstantVisitor {
     addRoot(constant.dispatchedType.element.name);
     add('methods');
   }
+
+  visitDummyReceiver(DummyReceiverConstant constant) {
+    add('dummy_receiver');
+  }
 }
 
 /**
@@ -1258,6 +1262,11 @@ class ConstantCanonicalHasher implements ConstantVisitor<int> {
     return _hashString(5, typeName);
   }
 
+  visitDummyReceiver(DummyReceiverConstant constant) {
+    compiler.internalError(
+        'DummyReceiverConstant should never be named and never be subconstant');
+  }
+
   int _hashString(int hash, String s) {
     int length = s.length;
     hash = _combine(hash, length);