Implement dynamic and void as types exported by core library.

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

Index: pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.dart
index b675255092ade45252f24370ef4bcb4bb7c91c0b..3075d00b5623a7ea21852f837b4a5c0daa9bfc09 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.dart
@@ -24,9 +24,9 @@ import '../util/relativize.dart' show relativizeUri;
 import 'kernel_builder.dart'
     show
         Builder,
+        BuiltinTypeBuilder,
         ClassBuilder,
         ConstructorReferenceBuilder,
-        DynamicTypeBuilder,
         FormalParameterBuilder,
         FunctionTypeAliasBuilder,
         KernelConstructorBuilder,
@@ -75,15 +75,8 @@ class KernelLibraryBuilder
 
   KernelTypeBuilder addNamedType(
       String name, List<KernelTypeBuilder> arguments, int charOffset) {
-    KernelNamedTypeBuilder type =
-        new KernelNamedTypeBuilder(name, arguments, charOffset, fileUri);
-    if (identical(name, "dynamic")) {
-      type.builder =
-          new DynamicTypeBuilder(const DynamicType(), this, charOffset);
-    } else {
-      addType(type);
-    }
-    return type;
+    return addType(
+        new KernelNamedTypeBuilder(name, arguments, charOffset, fileUri));
   }
 
   KernelTypeBuilder addMixinApplication(KernelTypeBuilder supertype,
@@ -94,7 +87,7 @@ class KernelLibraryBuilder
   }
 
   KernelTypeBuilder addVoidType(int charOffset) {
-    return new KernelNamedTypeBuilder("void", null, charOffset, fileUri);
+    return addNamedType("void", null, charOffset);
   }
 
   void addClass(
@@ -314,6 +307,8 @@ class KernelLibraryBuilder
       library.addClass(builder.build(this));
     } else if (builder is PrefixBuilder) {
       // Ignored. Kernel doesn't represent prefixes.
+    } else if (builder is BuiltinTypeBuilder) {
+      // Nothing needed.
     } else {
       internalError("Unhandled builder: ${builder.runtimeType}");
     }