Don't return values that aren't used.

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 14 matching lines @@
     SourceClassBuilder;
 
 import '../util/relativize.dart' show
     relativizeUri;
 
 import 'kernel_builder.dart' show
     Builder,
     ClassBuilder,
     ConstructorReferenceBuilder,
     DynamicTypeBuilder,
-    EnumBuilder,
-    FieldBuilder,
     FormalParameterBuilder,
     FunctionTypeAliasBuilder,
     KernelEnumBuilder,
     KernelFieldBuilder,
     KernelFormalParameterBuilder,
     KernelFunctionTypeAliasBuilder,
     KernelInvalidTypeBuilder,
     KernelMixinApplicationBuilder,
     KernelNamedMixinApplicationBuilder,
     KernelNamedTypeBuilder,
     KernelProcedureBuilder,
     KernelTypeBuilder,
     KernelTypeVariableBuilder,
     MemberBuilder,
     MetadataBuilder,
     MixedAccessor,
     NamedMixinApplicationBuilder,
     PrefixBuilder,
-    ProcedureBuilder,
     TypeVariableBuilder;
 
 class KernelLibraryBuilder
     extends SourceLibraryBuilder<KernelTypeBuilder, Library> {
   final Library library;
 
   final List<Class> mixinApplicationClasses = <Class>[];
 
   final List<List> argumentsWithMissingDefaultValues = <List>[];
 
@@ skipping 20 matching lines @@
       List<KernelTypeBuilder> mixins, int charOffset) {
     KernelTypeBuilder type = new KernelMixinApplicationBuilder(
         supertype, mixins, charOffset, fileUri);
     return addType(type);
   }
 
   KernelTypeBuilder addVoidType(int charOffset) {
     return new KernelNamedTypeBuilder("void", null, charOffset, fileUri);
   }
 
-  ClassBuilder addClass(List<MetadataBuilder> metadata,
+  void addClass(List<MetadataBuilder> metadata,
       int modifiers, String className,
       List<TypeVariableBuilder> typeVariables, KernelTypeBuilder supertype,
       List<KernelTypeBuilder> interfaces, int charOffset) {
     ClassBuilder cls = new SourceClassBuilder(metadata, modifiers, className,
         typeVariables, supertype, interfaces, classMembers, declarationTypes,
         this,
         new List<ConstructorReferenceBuilder>.from(constructorReferences),
         charOffset);
     constructorReferences.clear();
     classMembers.forEach((String name, MemberBuilder builder) {
       while (builder != null) {
         builder.parent = cls;
         builder = builder.next;
       }
     });
     // Nested declaration began in `OutlineBuilder.beginClassDeclaration`.
     endNestedDeclaration();
-    return addBuilder(className, cls);
+    addBuilder(className, cls);
   }
 
-  NamedMixinApplicationBuilder addNamedMixinApplication(
+  void addNamedMixinApplication(
       List<MetadataBuilder> metadata, String name,
       List<TypeVariableBuilder> typeVariables, int modifiers,
       KernelTypeBuilder mixinApplication, List<KernelTypeBuilder> interfaces,
       int charOffset) {
     NamedMixinApplicationBuilder builder =
         new KernelNamedMixinApplicationBuilder(metadata, name, typeVariables,
             modifiers, mixinApplication, interfaces, declarationTypes, this,
             charOffset);
     // Nested declaration began in `OutlineBuilder.beginNamedMixinApplication`.
     endNestedDeclaration();
-    return addBuilder(name, builder);
+    addBuilder(name, builder);
   }
 
-  FieldBuilder addField(List<MetadataBuilder> metadata,
+  void addField(List<MetadataBuilder> metadata,
       int modifiers, KernelTypeBuilder type, String name, int charOffset) {
-    return addBuilder(name, new KernelFieldBuilder(
+    addBuilder(name, new KernelFieldBuilder(
             metadata, type, name, modifiers, this, charOffset));
   }
 
-  ProcedureBuilder addProcedure(List<MetadataBuilder> metadata,
+  void addProcedure(List<MetadataBuilder> metadata,
       int modifiers, KernelTypeBuilder returnType, String name,
       List<TypeVariableBuilder> typeVariables,
       List<FormalParameterBuilder> formals, AsyncMarker asyncModifier,
       ProcedureKind kind, int charOffset) {
     // Nested declaration began in `OutlineBuilder.beginMethod` or
     // `OutlineBuilder.beginTopLevelMethod`.
     endNestedDeclaration().resolveTypes(typeVariables);
-    return addBuilder(name,
+    addBuilder(name,
         new KernelProcedureBuilder(metadata, modifiers, returnType, name,
             typeVariables, formals, asyncModifier, kind, this, charOffset));
   }
 
   void addFactoryMethod(List<MetadataBuilder> metadata,
       ConstructorReferenceBuilder constructorName,
       List<FormalParameterBuilder> formals, AsyncMarker asyncModifier,
       ConstructorReferenceBuilder redirectionTarget, int charOffset) {
     String name = constructorName.name;
     assert(constructorName.suffix == null);
     addBuilder(name,
         new KernelProcedureBuilder(metadata, staticMask, null, name, null,
             formals, asyncModifier, ProcedureKind.Factory, this, charOffset,
             redirectionTarget));
   }
 
-  EnumBuilder addEnum(List<MetadataBuilder> metadata, String name,
+  void addEnum(List<MetadataBuilder> metadata, String name,
       List<String> constants, int charOffset) {
-    return addBuilder(name,
+    addBuilder(name,
         new KernelEnumBuilder(metadata, name, constants, this, charOffset));
   }
 
-  FunctionTypeAliasBuilder addFunctionTypeAlias(List<MetadataBuilder> metadata,
+  void addFunctionTypeAlias(List<MetadataBuilder> metadata,
       KernelTypeBuilder returnType, String name,
       List<TypeVariableBuilder> typeVariables,
       List<FormalParameterBuilder> formals, int charOffset) {
     FunctionTypeAliasBuilder typedef = new KernelFunctionTypeAliasBuilder(
         metadata, returnType, name, typeVariables, formals, declarationTypes,
         this, charOffset);
     // Nested declaration began in `OutlineBuilder.beginFunctionTypeAlias`.
     endNestedDeclaration();
-    return addBuilder(name, typedef);
+    addBuilder(name, typedef);
   }
 
   KernelFormalParameterBuilder addFormalParameter(
       List<MetadataBuilder> metadata, int modifiers,
       KernelTypeBuilder type, String name, bool hasThis, int charOffset) {
     return new KernelFormalParameterBuilder(
         metadata, modifiers, type, name, hasThis, this, charOffset);
   }
 
   KernelTypeVariableBuilder addTypeVariable(String name,
@@ skipping 94 matching lines @@
           }
           expression.value =
               defaultArgumentFrom(names[expression.name].initializer)
               ..parent = expression;
         }
       }
     }
     return argumentsWithMissingDefaultValues.length;
   }
 }