Infer types of final fields.

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 602 matching lines @@
       // initializer list.
       isFinalOrConst = true;
     }
     HFieldGet result = new HFieldGet(
         field, node.inputs[0], isAssignable: !isFinalOrConst);
 
     if (field.getEnclosingClass().isNative()) {
       result.instructionType =
           new HType.subtype(field.computeType(compiler), compiler);
     } else {
-      HType type = backend.optimisticFieldType(field);
+      HType type = new HType.inferredForElement(field, compiler);
+      if (type.isUnknown()) {
+        type = backend.optimisticFieldType(field);
+        if (type != null) {
+          backend.registerFieldTypesOptimization(
+              work.element, field, result.instructionType);
+        }
+      }
       if (type != null) {
-        backend.registerFieldTypesOptimization(
-            work.element, field, result.instructionType);
         result.instructionType = type;
       }
     }
     return result;
   }
 
   HInstruction visitInvokeDynamicSetter(HInvokeDynamicSetter node) {
     if (node.isInterceptorCall) return handleInterceptorCall(node);
 
     Element field =
@@ skipping 884 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.
   }
 }