Use the explicit string 'dynamic' to refer to dynamic in summaries.

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

Index: pkg/analyzer/lib/src/summary/format.dart
diff --git a/pkg/analyzer/lib/src/summary/format.dart b/pkg/analyzer/lib/src/summary/format.dart
index 0a771c25c549b9e9acace51ee2d84a462fdf22a0..ab62062d4b44ba972cec1bdcc788b3cded753796 100644
--- a/pkg/analyzer/lib/src/summary/format.dart
+++ b/pkg/analyzer/lib/src/summary/format.dart
@@ -447,12 +447,6 @@ class EntityRefBuilder extends Object with _EntityRefMixin implements EntityRef
   /**
    * Index into [UnlinkedUnit.references] for the entity being referred to, or
    * zero if this is a reference to a type parameter.
-   *
-   * Note that since zero is also a valid index into
-   * [UnlinkedUnit.references], we cannot distinguish between references to
-   * type parameters and references to other entities by checking [reference]
-   * against zero.  To distinguish between references to type parameters and
-   * references to other entities, check whether [paramReference] is zero.
    */
   void set reference(int _value) {
     assert(!_finished);
@@ -549,12 +543,6 @@ abstract class EntityRef extends base.SummaryClass {
   /**
    * Index into [UnlinkedUnit.references] for the entity being referred to, or
    * zero if this is a reference to a type parameter.
-   *
-   * Note that since zero is also a valid index into
-   * [UnlinkedUnit.references], we cannot distinguish between references to
-   * type parameters and references to other entities by checking [reference]
-   * against zero.  To distinguish between references to type parameters and
-   * references to other entities, check whether [paramReference] is zero.
    */
   int get reference;
 
@@ -1252,8 +1240,8 @@ class LinkedReferenceBuilder extends Object with _LinkedReferenceMixin implement
 
   /**
    * If this [LinkedReference] doesn't have an associated [UnlinkedReference],
-   * name of the entity being referred to.  The empty string refers to the
-   * pseudo-type `dynamic`.
+   * name of the entity being referred to.  For the pseudo-type `dynamic`, the
+   * string is "dynamic".
    */
   void set name(String _value) {
     assert(!_finished);
@@ -1327,8 +1315,8 @@ abstract class LinkedReference extends base.SummaryClass {
 
   /**
    * If this [LinkedReference] doesn't have an associated [UnlinkedReference],
-   * name of the entity being referred to.  The empty string refers to the
-   * pseudo-type `dynamic`.
+   * name of the entity being referred to.  For the pseudo-type `dynamic`, the
+   * string is "dynamic".
    */
   String get name;
 }
@@ -4661,8 +4649,8 @@ class UnlinkedReferenceBuilder extends Object with _UnlinkedReferenceMixin imple
   String get name => _name ??= '';
 
   /**
-   * Name of the entity being referred to.  The empty string refers to the
-   * pseudo-type `dynamic`.
+   * Name of the entity being referred to.  For the pseudo-type `dynamic`, the
+   * string is "dynamic".
    */
   void set name(String _value) {
     assert(!_finished);
@@ -4715,8 +4703,8 @@ class UnlinkedReferenceBuilder extends Object with _UnlinkedReferenceMixin imple
 abstract class UnlinkedReference extends base.SummaryClass {
 
   /**
-   * Name of the entity being referred to.  The empty string refers to the
-   * pseudo-type `dynamic`.
+   * Name of the entity being referred to.  For the pseudo-type `dynamic`, the
+   * string is "dynamic".
    */
   String get name;
 
@@ -5225,8 +5213,10 @@ class UnlinkedUnitBuilder extends Object with _UnlinkedUnitMixin implements Unli
 
   /**
    * Top level and prefixed names referred to by this compilation unit.  The
-   * zeroth element of this array is always populated and always represents a
-   * reference to the pseudo-type "dynamic".
+   * zeroth element of this array is always populated and is used to represent
+   * the absence of a reference in places where a reference is optional (for
+   * example [UnlinkedReference.prefixReference or
+   * UnlinkedImport.prefixReference]).
    */
   void set references(List<UnlinkedReferenceBuilder> _value) {
     assert(!_finished);
@@ -5480,8 +5470,10 @@ abstract class UnlinkedUnit extends base.SummaryClass {
 
   /**
    * Top level and prefixed names referred to by this compilation unit.  The
-   * zeroth element of this array is always populated and always represents a
-   * reference to the pseudo-type "dynamic".
+   * zeroth element of this array is always populated and is used to represent
+   * the absence of a reference in places where a reference is optional (for
+   * example [UnlinkedReference.prefixReference or
+   * UnlinkedImport.prefixReference]).
    */
   List<UnlinkedReference> get references;