Add summary support for ShowElementCombinator.end and .offset.

pkg/analyzer/lib/src/summary/idl.dart

Index: pkg/analyzer/lib/src/summary/idl.dart
diff --git a/pkg/analyzer/lib/src/summary/idl.dart b/pkg/analyzer/lib/src/summary/idl.dart
index 157819487f02fda2798ffb096786084daa086ce2..e49cf9b5152cb33a65cb65178ec00410c453dced 100644
--- a/pkg/analyzer/lib/src/summary/idl.dart
+++ b/pkg/analyzer/lib/src/summary/idl.dart
@@ -549,12 +549,28 @@ abstract class UnlinkedClass extends base.SummaryClass {
  */
 abstract class UnlinkedCombinator extends base.SummaryClass {
   /**
+   * If this is a `show` combinator, offset of the end of the list of shown
+   * names.  Otherwise zero.
+   */
+  @informative
+  @Id(3)
+  int get end;
+
+  /**
    * List of names which are hidden.  Empty if this is a `show` combinator.
    */
   @Id(1)
   List<String> get hides;
 
   /**
+   * If this is a `show` combinator, offset of the `show` keyword.  Otherwise
+   * zero.
+   */
+  @informative
+  @Id(2)
+  int get offset;
+
+  /**
    * List of names which are shown.  Empty if this is a `hide` combinator.
    */
   @Id(0)