Deprecate utility method

pkg/analyzer/lib/src/generated/element.dart

Index: pkg/analyzer/lib/src/generated/element.dart
diff --git a/pkg/analyzer/lib/src/generated/element.dart b/pkg/analyzer/lib/src/generated/element.dart
index 79a8129e27bb49d7ec6f7cab84c55593dbc725d0..d8061b90a054ab5e96ce73cdaaefb9ac303ab608 100644
--- a/pkg/analyzer/lib/src/generated/element.dart
+++ b/pkg/analyzer/lib/src/generated/element.dart
@@ -7093,10 +7093,9 @@ class LibraryElementImpl extends ElementImpl implements LibraryElement {
 
   @override
   List<CompilationUnitElement> get units {
-    List<CompilationUnitElement> units =
-        new List<CompilationUnitElement>(1 + _parts.length);
-    units[0] = _definingCompilationUnit;
-    JavaSystem.arraycopy(_parts, 0, units, 1, _parts.length);
+    List<CompilationUnitElement> units = new List<CompilationUnitElement>();
+    units.add(_definingCompilationUnit);
+    units.addAll(_parts);
     return units;
   }