Remove unused private methods in interpreter

pkg/kernel/lib/interpreter/interpreter.dart

Index: pkg/kernel/lib/interpreter/interpreter.dart
diff --git a/pkg/kernel/lib/interpreter/interpreter.dart b/pkg/kernel/lib/interpreter/interpreter.dart
index 1889b3645e19f2735733aafc6220ad9f38f6ae02..9617af5260906bbaa533e744b92c9829ab6c4dc1 100644
--- a/pkg/kernel/lib/interpreter/interpreter.dart
+++ b/pkg/kernel/lib/interpreter/interpreter.dart
@@ -1292,27 +1292,3 @@ List<InterpreterExpression> _createArgumentExpressionList(
 
   return args;
 }
-
-Expression _getExpression(Initializer initializer) {
-  if (initializer is FieldInitializer) {
-    return initializer.value;
-  }
-  if (initializer is LocalInitializer) {
-    return initializer.variable.initializer;
-  }
-
-  throw '${initializer.runtimeType} has no epxression.';
-}
-
-/// Initializes all non initialized fields in given class with
-/// [Value.nullInstance].
-void _initializeNullFields(Class class_, ObjectValue newObject) {
-  int superClassSize = class_.superclass?.instanceSize ?? 0;
-  for (int i = superClassSize; i < class_.instanceSize; i++) {
-    Field field = class_.instanceFields[i];
-    if (class_.getProperty(newObject, field) == null) {
-      assert(field.initializer == null);
-      class_.setProperty(newObject, field, Value.nullInstance);
-    }
-  }
-}