Address additional comments on nullability

pkg/dev_compiler/lib/src/compiler/reify_coercions.dart

Index: pkg/dev_compiler/lib/src/compiler/reify_coercions.dart
diff --git a/pkg/dev_compiler/lib/src/compiler/reify_coercions.dart b/pkg/dev_compiler/lib/src/compiler/reify_coercions.dart
index bf0b57110a7660b8169ae552b718ce7155328234..6b2e88d0435a4fdc76d2a85257e823d42009e4f5 100644
--- a/pkg/dev_compiler/lib/src/compiler/reify_coercions.dart
+++ b/pkg/dev_compiler/lib/src/compiler/reify_coercions.dart
@@ -121,8 +121,8 @@ class CoercionReifier extends analyzer.GeneralizingAstVisitor<Object> {
     }
   }
 
-  /*=T*/ _clone/*<T extends AstNode>*/(/*=T*/ node) {
-    var copy = node.accept(cloner) as dynamic/*=T*/;
+  T _clone<T extends AstNode>(T node) {
+    var copy = node.accept(cloner) as T;
     ResolutionCopier.copyResolutionData(node, copy);
     return copy;
   }
@@ -147,14 +147,14 @@ class _TreeCloner extends analyzer.AstCloner {
   }
 
   @override
-  /*=E*/ cloneNode/*<E extends AstNode>*/(/*=E*/ node) {
+  E cloneNode<E extends AstNode>(E node) {
     var clone = super.cloneNode(node);
     _cloneProperties(clone, node);
     return clone;
   }
 
   @override
-  List/*<E>*/ cloneNodeList/*<E extends AstNode>*/(List/*<E>*/ list) {
+  List<E> cloneNodeList<E extends AstNode>(List<E> list) {
     var clone = super.cloneNodeList(list);
     for (int i = 0, len = list.length; i < len; i++) {
       _cloneProperties(clone[i], list[i]);