Prepare for development branch by updating externally-used API.

pkg/front_end/lib/src/fasta/scope.dart

Index: pkg/front_end/lib/src/fasta/scope.dart
diff --git a/pkg/front_end/lib/src/fasta/scope.dart b/pkg/front_end/lib/src/fasta/scope.dart
index 2dd1656ef0bf633fb525fc4f7574981daa07c032..0910f76c847287e6b264473b58ba15ccf7174c66 100644
--- a/pkg/front_end/lib/src/fasta/scope.dart
+++ b/pkg/front_end/lib/src/fasta/scope.dart
@@ -6,7 +6,7 @@ library fasta.scope;
 
 import 'builder/builder.dart' show Builder, TypeVariableBuilder;
 
-import 'errors.dart' show internalError;
+import 'errors.dart' show InputError, internalError;
 
 class MutableScope {
   /// Names declared in this scope.
@@ -167,13 +167,14 @@ class Scope extends MutableScope {
     return (labels == null ? null : labels[name]) ?? parent?.lookupLabel(name);
   }
 
-  // TODO(ahe): Rename to extend or something.
-  void operator []=(String name, Builder member) {
+  InputError declare(
+      String name, Builder builder, int charOffset, Uri fileUri) {

[scheglov, 2017/05/23 16:14:45]

Please document the method and meaning of the parameters.

[ahe, 2017/05/24 10:54:20]

Done.

     if (isModifiable) {
       local[name] = member;
     } else {
       internalError("Can't extend an unmodifiable scope.");
     }
+    return null;

[ahe, 2017/05/23 15:04:24]

Will eventually return an InputError if the name is already used in this scope.

   }
 
   void merge(Scope scope,