Remove deprecated string features.

tests/language/optimized_constant_array_string_access_test.dart

Index: tests/language/optimized_constant_array_string_access_test.dart
diff --git a/tests/language/optimized_constant_array_string_access_test.dart b/tests/language/optimized_constant_array_string_access_test.dart
index 2e0b1ba44da0f306136fc3cae5001c0ec7dd5776..391d971286f09ef33429b55b69873bf0c4598f88 100644
--- a/tests/language/optimized_constant_array_string_access_test.dart
+++ b/tests/language/optimized_constant_array_string_access_test.dart
@@ -4,10 +4,10 @@
 
 // Test optimized constant string and constant array access.
 
-int testConstantStringAndIndexCharCodeAt() {
+int testConstantStringAndIndexCodeUnitAt() {
   int test(b) {
-    if (b) return "hest".charCodeAt(400);
-    return "hest".charCodeAt(2);
+    if (b) return "hest".codeUnitAt(400);
+    return "hest".codeUnitAt(2);
   }
 
   Expect.throws(() => test(true));
@@ -43,7 +43,7 @@ int testNonSmiIndex() {
 
 
 main() {
-  testConstantStringAndIndexCharCodeAt();
+  testConstantStringAndIndexCodeUnitAt();
   testConstantArrayAndIndexAt();
   testNonSmiIndex();
 }