Fix incremental element builder for added enums.

pkg/analyzer/lib/src/task/incremental_element_builder.dart

Index: pkg/analyzer/lib/src/task/incremental_element_builder.dart
diff --git a/pkg/analyzer/lib/src/task/incremental_element_builder.dart b/pkg/analyzer/lib/src/task/incremental_element_builder.dart
index 54d0ac5252fd56a887594554c21a6103a0582953..7e5444d79214fb0c6dbcf8cb464abbc2f78dc528 100644
--- a/pkg/analyzer/lib/src/task/incremental_element_builder.dart
+++ b/pkg/analyzer/lib/src/task/incremental_element_builder.dart
@@ -133,6 +133,7 @@ class IncrementalCompilationUnitElementBuilder {
     _materializeLazyElements();
     new CompilationUnitBuilder()
         .buildCompilationUnit(unitSource, newUnit, librarySource);
+    newUnit.accept(new EnumMemberBuilder(unitElement.context.typeProvider));
     _processDirectives();
     _processUnitMembers();
     _replaceUnitContents(oldUnit, newUnit);