Improve compile-time error handling.

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 90 matching lines @@
         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();
-    addBuilder(className, cls);
+    addBuilder(className, cls, charOffset);
   }
 
   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();
-    addBuilder(name, builder);
+    addBuilder(name, builder, charOffset);
   }
 
   void addField(List<MetadataBuilder> metadata,
       int modifiers, KernelTypeBuilder type, String name, int charOffset) {
     addBuilder(name, new KernelFieldBuilder(
-            metadata, type, name, modifiers, this, charOffset));
+            metadata, type, name, modifiers, this, charOffset), charOffset);
   }
 
   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);
     addBuilder(name,
         new KernelProcedureBuilder(metadata, modifiers, returnType, name,
-            typeVariables, formals, asyncModifier, kind, this, charOffset));
+            typeVariables, formals, asyncModifier, kind, this, charOffset),
+        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));
+            redirectionTarget), charOffset);
   }
 
   void addEnum(List<MetadataBuilder> metadata, String name,
       List<String> constants, int charOffset) {
     addBuilder(name,
-        new KernelEnumBuilder(metadata, name, constants, this, charOffset));
+        new KernelEnumBuilder(metadata, name, constants, this, charOffset),
+        charOffset);
   }
 
   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();
-    addBuilder(name, typedef);
+    addBuilder(name, typedef, charOffset);
   }
 
   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;
   }
 }