Implement more fixes.

pkg/analysis_services/lib/src/correction/strings.dart

Index: pkg/analysis_services/lib/src/correction/strings.dart
diff --git a/pkg/analysis_services/lib/src/correction/strings.dart b/pkg/analysis_services/lib/src/correction/strings.dart
index 14887cc7395497f3bf2f0c5f354fe5f93896758c..02acad66346eeff450b3ddd02baa65d523bc849e 100644
--- a/pkg/analysis_services/lib/src/correction/strings.dart
+++ b/pkg/analysis_services/lib/src/correction/strings.dart
@@ -58,6 +58,19 @@ String removeStart(String str, String remove) {
   return str;
 }
 
+int compareStrings(String a, String b) {
+  if (a == b) {
+    return 0;
+  }
+  if (a == null) {
+    return 1;
+  }
+  if (b == null) {
+    return -1;
+  }
+  return a.compareTo(b);
+}
+
 String repeat(String s, int n) {
   StringBuffer sb = new StringBuffer();
   for (int i = 0; i < n; i++) {