After a dynamic call, refine the receiver type by looking at the potential targets of that call.

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 649 matching lines @@
     return node;
   }
 
   HInstruction visitInvokeDynamicGetter(HInvokeDynamicGetter node) {
     if (node.isInterceptedCall) {
       HInstruction folded = handleInterceptedCall(node);
       if (folded != node) return folded;
     }
     HInstruction receiver = node.getDartReceiver(compiler);
     Element field = findConcreteFieldForDynamicAccess(receiver, node.selector);
-    if (field == null) return node;
-    return directFieldGet(receiver, field);
+    if (field != null) return directFieldGet(receiver, field);
+    Selector selector = node.selector;
+    if (node.dependsOnSomething()
+        && compiler.resolverWorld.onlyReachesFinalFields(selector, compiler)) {
+      // If we know all potential targets are final fields, or fields
+      // that are never assigned twice, we know this getter does not
+      // depend on anything.
+      node.clearAllDependencies();
+    }
+    return node;
   }
 
   HInstruction directFieldGet(HInstruction receiver, Element field) {
     Modifiers modifiers = field.modifiers;
     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.
       isAssignable = false;
     }
@@ skipping 1024 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.
   }
 }