Emit compile-time error when a constant field is not initialized.

sdk/lib/_internal/compiler/implementation/resolution/members.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 resolution;
 
 abstract class TreeElements {
   Element get currentElement;
   Set<Node> get superUses;
 
@@ skipping 430 matching lines @@
 
   TreeElements resolveField(VariableElement element) {
     Node tree = element.parseNode(compiler);
     if(element.modifiers.isStatic() && element.variables.isTopLevel()) {
       error(element.modifiers.getStatic(),
             MessageKind.TOP_LEVEL_VARIABLE_DECLARED_STATIC);
     }
     ResolverVisitor visitor = visitorFor(element);
     visitor.useElement(tree, element);
 
-    // TODO(johnniwinther): Avoid analyzing initializers if
-    // [Compiler.analyzeSignaturesOnly] is set.
-    initializerDo(tree, visitor.visit);
+    SendSet send = tree.asSendSet();
+    if (send != null) {
+      if (!compiler.analyzeSignaturesOnly) {
+        visitor.visit(send.arguments.head);
+      }
+    } else if (element.modifiers.isConst()) {
+      compiler.reportError(element, MessageKind.CONST_WITHOUT_INITIALIZER);
+    }
 
     if (Elements.isStaticOrTopLevelField(element)) {
       if (tree.asSendSet() != null) {
         // TODO(13429): We could do better here by using the
         // constant handler to figure out if it's a lazy field or not.
         compiler.backend.registerLazyField(visitor.mapping);
       } else {
         compiler.enqueuer.resolution.registerInstantiatedClass(
             compiler.nullClass, visitor.mapping);
       }
@@ skipping 3918 matching lines @@
     return e;
   }
 
   /// Assumed to be called by [resolveRedirectingFactory].
   Element visitReturn(Return node) {
     Node expression = node.expression;
     return finishConstructorReference(visit(expression),
                                       expression, expression);
   }
 }