Remove deprecated string features.

tests/language/static_inline_test.dart

Index: tests/language/static_inline_test.dart
diff --git a/tests/language/static_inline_test.dart b/tests/language/static_inline_test.dart
index 4c5ad9a9f0c1661937b3c64a0bc50a64e0f7851f..5163b3d7d83770c49ee13c2f96d99d56999152b9 100644
--- a/tests/language/static_inline_test.dart
+++ b/tests/language/static_inline_test.dart
@@ -16,7 +16,7 @@ class StringScanner {
   }
 
   static int charAt(index)
-      => (string.length > index) ? string.charCodeAt(index) : -1;
+      => (string.length > index) ? string.codeUnitAt(index) : -1;
 }
 
 void main() {
@@ -26,4 +26,4 @@ void main() {
   Expect.equals(0x7A, scanner.nextByte(false)); // Expect z.
   Expect.equals(0x39, scanner.nextByte(false)); // Expect 9.
   Expect.equals(-1, scanner.nextByte(false));
-}
+}