Clean up use of identifier context.

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

 // Copyright (c) 2016, 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.
 
 library fasta.body_builder;
 
 import '../parser/parser.dart' show FormalParameterType, optional;
 
 import '../parser/error_kind.dart' show ErrorKind;
 
@@ skipping 735 matching lines @@
     debugEvent("handleIdentifier");
     String name = token.lexeme;
     if (context.isScopeReference) {
       assert(!inInitializer ||
           this.scope == enclosingScope ||
           this.scope.parent == enclosingScope);
       // This deals with this kind of initializer: `C(a) : a = a;`
       Scope scope = inInitializer ? enclosingScope : this.scope;
       Builder builder = scope.lookup(name, token.charOffset, uri);
       push(builderToFirstExpression(builder, name, token.charOffset));
-    } else {
-      if (constantExpressionRequired) {
-        if (context != IdentifierContext.namedArgumentReference &&
-            context != IdentifierContext.constructorReferenceContinuation &&
-            context != IdentifierContext.expressionContinuation &&
-            context != IdentifierContext.typeReferenceContinuation &&
-            context != IdentifierContext.localVariableDeclaration &&
-            context !=
-                IdentifierContext
-                    .constructorReferenceContinuationAfterTypeArguments) {
-          addCompileTimeError(
-              token.charOffset, "Not a constant expression: $context");
-        }
+      return;
+    } else if (context.inDeclaration) {
+      if (context == IdentifierContext.topLevelVariableDeclaration ||
+          context == IdentifierContext.fieldDeclaration) {
+        constantExpressionRequired = member.isConst;
       }
-      push(new Identifier(name)..fileOffset = token.charOffset);
+    } else if (constantExpressionRequired &&
+        !context.allowedInConstantExpression) {
+      addCompileTimeError(
+          token.charOffset, "Not a constant expression: $context");
     }
+    push(new Identifier(name)..fileOffset = token.charOffset);
   }
 
   @override
   builderToFirstExpression(Builder builder, String name, int charOffset,
       {bool isPrefix: false}) {
     if (builder == null || (!isInstanceContext && builder.isInstanceMember)) {
       Name n = new Name(name, library.library);
       if (!isPrefix && isInstanceContext) {
         assert(builder == null);
         if (constantExpressionRequired) {
@@ skipping 2094 matching lines @@
   } else if (node is PrefixBuilder) {
     return node.name;
   } else if (node is ThisAccessor) {
     return node.isSuper ? "super" : "this";
   } else if (node is BuilderAccessor) {
     return node.plainNameForRead;
   } else {
     return internalError("Unhandled: ${node.runtimeType}");
   }
 }