Add summary support for ParameterElement.defaultValueCode.

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 5c422aed30b94b07da55169cfafc44348bcba2aa..ed9a3e3a842e5ef410f196e4cc3c5ec0a73eb0ac 100644
--- a/pkg/analyzer/lib/src/summary/idl.dart
+++ b/pkg/analyzer/lib/src/summary/idl.dart
@@ -1482,6 +1482,14 @@ abstract class UnlinkedParam extends base.SummaryClass {
   int get nameOffset;
 
   /**
+   * If the parameter has a default value, the source text of the constant
+   * expression in the default value.  Otherwise the empty string.
+   */
+  @informative
+  @Id(13)
+  String get defaultValueCode;
+
+  /**
    * If [isFunctionTyped] is `true`, the parameters of the function type.
    */
   @Id(8)