All strong mode cleaning of dart2js.

pkg/compiler/lib/src/universe/codegen_world_builder.dart

Index: pkg/compiler/lib/src/universe/codegen_world_builder.dart
diff --git a/pkg/compiler/lib/src/universe/codegen_world_builder.dart b/pkg/compiler/lib/src/universe/codegen_world_builder.dart
index 7df0e20de6ec1083905453b37d35fb6e1673f625..67da175c0f895e837b5f04858eacd5a21a353690 100644
--- a/pkg/compiler/lib/src/universe/codegen_world_builder.dart
+++ b/pkg/compiler/lib/src/universe/codegen_world_builder.dart
@@ -10,12 +10,12 @@ part of world_builder;
 abstract class CodegenWorldBuilder implements WorldBuilder {
   /// Calls [f] with every instance field, together with its declarer, in an
   /// instance of [cls].
-  void forEachInstanceField(
-      ClassEntity cls, void f(ClassEntity declarer, FieldEntity field));
+  void forEachInstanceField(covariant ClassEntity cls,
+      void f(ClassEntity declarer, FieldEntity field));
 
   /// Calls [f] for each parameter of [function] providing the type and name of
   /// the parameter and the [defaultValue] if the parameter is optional.
-  void forEachParameter(FunctionEntity function,
+  void forEachParameter(covariant FunctionEntity function,
       void f(DartType type, String name, ConstantValue defaultValue));
 
   void forEachInvokedName(
@@ -28,7 +28,7 @@ abstract class CodegenWorldBuilder implements WorldBuilder {
       f(String name, Map<Selector, SelectorConstraints> selectors));
 
   /// Returns `true` if [field] constant or final with a constant initializer.
-  bool hasConstantFieldInitializer(FieldEntity field);
+  bool hasConstantFieldInitializer(covariant FieldEntity field);
 
   /// Returns `true` if [member] is invoked as a setter.
   bool hasInvokedSetter(MemberEntity member, ClosedWorld world);
@@ -323,7 +323,7 @@ abstract class CodegenWorldBuilderImpl implements CodegenWorldBuilder {
     _invokedSetters.forEach(f);
   }
 
-  void registerIsCheck(DartType type) {
+  void registerIsCheck(covariant DartType type) {
     isChecks.add(type.unaliased);
   }
 
@@ -420,14 +420,14 @@ abstract class CodegenWorldBuilderImpl implements CodegenWorldBuilder {
     });
   }
 
-  void _processInstantiatedClassMember(
-      ClassEntity cls, MemberEntity member, MemberUsedCallback memberUsed) {
+  void _processInstantiatedClassMember(ClassEntity cls,
+      covariant MemberEntity member, MemberUsedCallback memberUsed) {
     if (!member.isInstanceMember) return;
     _getMemberUsage(member, memberUsed);
   }
 
   _MemberUsage _getMemberUsage(
-      MemberEntity member, MemberUsedCallback memberUsed) {
+      covariant MemberEntity member, MemberUsedCallback memberUsed) {
     return _instanceMemberUsage.putIfAbsent(member, () {
       String memberName = member.name;
       ClassEntity cls = member.enclosingClass;