Element model support for covariant

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

Index: pkg/analyzer/lib/src/summary/link.dart
diff --git a/pkg/analyzer/lib/src/summary/link.dart b/pkg/analyzer/lib/src/summary/link.dart
index a685504be5cbc9ab8b18aacfae880c24708a91de..7dde331c6ce5729b31bdf3d20a11502576b46e1e 100644
--- a/pkg/analyzer/lib/src/summary/link.dart
+++ b/pkg/analyzer/lib/src/summary/link.dart
@@ -3859,7 +3859,7 @@ class ParameterElementForLink implements ParameterElementImpl {
 
   @override
   bool get isCovariant {
-    if (inheritsCovariant) {
+    if (isExplicitlyCovariant || inheritsCovariant) {
       return true;
     }
     for (UnlinkedExpr annotation in _unlinkedParam.annotations) {
@@ -3878,6 +3878,9 @@ class ParameterElementForLink implements ParameterElementImpl {
   }
 
   @override
+  bool get isExplicitlyCovariant => _unlinkedParam.isExplicitlyCovariant;
+
+  @override
   String get name => _unlinkedParam.name;
 
   @override
@@ -3955,7 +3958,10 @@ class ParameterElementForLink_VariableSetter implements ParameterElementImpl {
   ParameterElementForLink_VariableSetter(this.enclosingElement);
 
   @override
-  bool get isCovariant => false;
+  bool get isCovariant => isExplicitlyCovariant || inheritsCovariant;
+
+  @override
+  bool get isExplicitlyCovariant => enclosingElement.variable.isCovariant;
 
   @override
   bool get isSynthetic => true;
@@ -4909,6 +4915,12 @@ abstract class VariableElementForLink
   @override
   bool get isConst => unlinkedVariable.isConst;
 
+  /**
+   * Return `true` if this variable is a field that was explicitly marked as
+   * being covariant (in the setter's parameter).
+   */
+  bool get isCovariant => unlinkedVariable.isCovariant;
+
   @override
   bool get isFinal => unlinkedVariable.isFinal;