Rationalize coercions

test/codegen/expect/methods.txt

Index: test/codegen/expect/methods.txt
diff --git a/test/codegen/expect/methods.txt b/test/codegen/expect/methods.txt
index 870720340b0159cf7b5ab89a5ff0029b655639e2..f7b406fe6da40d7e47fec42297cf56371530212c 100644
--- a/test/codegen/expect/methods.txt
+++ b/test/codegen/expect/methods.txt
@@ -1,8 +1,8 @@
 // Messages from compiling methods.dart
-info: line 14, column 21 of test/codegen/methods.dart: [DownCast] b (num) will need runtime check to cast to type int
+warning: line 14, column 21 of test/codegen/methods.dart: [DownCastImplicit] b (num) will need runtime check to cast to type int
   int z([num b]) => b;
                     ^
-info: line 19, column 12 of test/codegen/methods.dart: [DownCast] a + b (num) will need runtime check to cast to type int
+warning: line 19, column 12 of test/codegen/methods.dart: [DownCastImplicit] a + b (num) will need runtime check to cast to type int
     return a + b;
            ^^^^^
 warning: line 49, column 3 of test/codegen/methods.dart: [DynamicInvoke] f.bar("Bar's call method!") requires dynamic invoke