All strong mode cleaning of dart2js.

pkg/compiler/lib/src/kernel/element_map.dart

Index: pkg/compiler/lib/src/kernel/element_map.dart
diff --git a/pkg/compiler/lib/src/kernel/element_map.dart b/pkg/compiler/lib/src/kernel/element_map.dart
index 84c16d251e9913d5087787791be3bb5c004169cd..03e89611f85930465e4a4cf1f777d80c9b0d22f0 100644
--- a/pkg/compiler/lib/src/kernel/element_map.dart
+++ b/pkg/compiler/lib/src/kernel/element_map.dart
@@ -83,7 +83,7 @@ abstract class KernelToElementMap {
   MemberEntity getMember(ir.Member node);
 
   /// Returns the kernel IR node that defines the [member].
-  ir.Member getMemberNode(MemberEntity member);
+  ir.Node getMemberNode(covariant MemberEntity member);
 
   /// Returns the [FunctionEntity] corresponding to the procedure [node].
   FunctionEntity getMethod(ir.Procedure node);
@@ -979,8 +979,8 @@ abstract class KernelToTypeInferenceMap {
   TypeMask typeOfSet(ir.PropertySet write, ClosedWorld closedWorld);
 
   /// Returns the inferred type of [listLiteral].
-  TypeMask typeOfListLiteral(
-      MemberEntity owner, ir.ListLiteral listLiteral, ClosedWorld closedWorld);
+  TypeMask typeOfListLiteral(covariant MemberEntity owner,
+      ir.ListLiteral listLiteral, ClosedWorld closedWorld);
 
   /// Returns the inferred type of iterator in [forInStatement].
   TypeMask typeOfIterator(ir.ForInStatement forInStatement);
@@ -1026,10 +1026,10 @@ abstract class KernelToLocalsMap {
   // TODO(johnniwinther): Make these return the [KernelToLocalsMap] to use from
   // now on.
   /// Call to notify that [member] is currently being inlined.
-  void enterInlinedMember(MemberEntity member);
+  void enterInlinedMember(covariant MemberEntity member);
 
   /// Call to notify that [member] is no longer being inlined.
-  void leaveInlinedMember(MemberEntity member);
+  void leaveInlinedMember(covariant MemberEntity member);
 
   /// Returns the [Local] for [node].
   Local getLocal(ir.VariableDeclaration node);