Compute correct return type for factory methods.

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

Index: pkg/front_end/lib/src/fasta/kernel/body_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
index 0fd71b135cb05f70750a66a1ef317deb1b1913d2..aa73589e5226bcc93c922e6977337093c347159b 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -485,9 +485,6 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
 
   DartType _computeReturnTypeContext(MemberBuilder member) {
     if (member is KernelProcedureBuilder) {
-      if (member.target.kind == ProcedureKind.Factory) {
-        return computeFactoryConstructorReturnType(member.target);
-      }
       return member.target.function.returnType;
     } else {
       assert(member is KernelConstructorBuilder);