Handle bad factory names correctly.

pkg/front_end/lib/src/fasta/kernel/kernel_library_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.kernel_library_builder;
 
 import 'package:kernel/ast.dart';
 
 import 'package:kernel/clone.dart' show CloneVisitor;
 
@@ skipping 135 matching lines @@
 
   void addField(List<MetadataBuilder> metadata, int modifiers,
       KernelTypeBuilder type, String name, int charOffset) {
     addBuilder(
         name,
         new KernelFieldBuilder(
             metadata, type, name, modifiers, this, charOffset),
         charOffset);
   }
 
+  String computeConstructorName(String name) {
+    assert(isConstructorName(name, currentDeclaration.name));
+    int index = name.indexOf(".");
+    return index == -1 ? "" : name.substring(index + 1);
+  }
+
   void addProcedure(
       List<MetadataBuilder> metadata,
       int modifiers,
       KernelTypeBuilder returnType,
       String name,
       List<TypeVariableBuilder> typeVariables,
       List<FormalParameterBuilder> formals,
       AsyncMarker asyncModifier,
       ProcedureKind kind,
       int charOffset,
       int charEndOffset,
       String nativeMethodName,
       {bool isTopLevel}) {
     // Nested declaration began in `OutlineBuilder.beginMethod` or
     // `OutlineBuilder.beginTopLevelMethod`.
     endNestedDeclaration().resolveTypes(typeVariables, this);
     ProcedureBuilder procedure;
     if (!isTopLevel && isConstructorName(name, currentDeclaration.name)) {
-      int index = name.indexOf(".");
-      name = index == -1 ? "" : name.substring(index + 1);
+      name = computeConstructorName(name);
       procedure = new KernelConstructorBuilder(
           metadata,
           modifiers & ~abstractMask,
           returnType,
           name,
           typeVariables,
           formals,
           this,
           charOffset,
           charEndOffset,
@@ skipping 26 matching lines @@
       List<FormalParameterBuilder> formals,
       AsyncMarker asyncModifier,
       ConstructorReferenceBuilder redirectionTarget,
       int charOffset,
       int charEndOffset,
       String nativeMethodName) {
     // Nested declaration began in `OutlineBuilder.beginFactoryMethod`.
     DeclarationBuilder<KernelTypeBuilder> factoryDeclaration =
         endNestedDeclaration();
     String name = constructorName.name;
-    int index = name.indexOf(".");
-    name = index == -1 ? "" : name.substring(index + 1);
+    if (isConstructorName(name, currentDeclaration.name)) {
+      name = computeConstructorName(name);
+    }
     assert(constructorName.suffix == null);
     KernelProcedureBuilder procedure = new KernelProcedureBuilder(
         metadata,
         staticMask | modifiers,
         null,
         name,
         <TypeVariableBuilder>[],
         formals,
         asyncModifier,
         ProcedureKind.Factory,
@@ skipping 193 matching lines @@
   }
 }
 
 bool isConstructorName(String name, String className) {
   if (name.startsWith(className)) {
     if (name.length == className.length) return true;
     if (name.startsWith(".", className.length)) return true;
   }
   return false;
 }