Enhance the change builders

pkg/analysis_server/lib/src/utilities/change_builder_core.dart

Index: pkg/analysis_server/lib/src/utilities/change_builder_core.dart
diff --git a/pkg/analysis_server/lib/src/utilities/change_builder_core.dart b/pkg/analysis_server/lib/src/utilities/change_builder_core.dart
index c91a8325032006c44c287dca8ce63e2128251bab..919388ea7a50aebe798523d8263a84a896f4814b 100644
--- a/pkg/analysis_server/lib/src/utilities/change_builder_core.dart
+++ b/pkg/analysis_server/lib/src/utilities/change_builder_core.dart
@@ -214,6 +214,26 @@ class FileEditBuilderImpl implements FileEditBuilder {
     }
   }
 
+  @override
+  void addSimpleInsertion(int offset, String text) {
+    EditBuilderImpl builder = createEditBuilder(offset, 0);
+    try {
+      builder.write(text);
+    } finally {
+      fileEdit.add(builder.sourceEdit);
+    }
+  }
+
+  @override
+  void addSimpleReplacement(int offset, int length, String text) {
+    EditBuilderImpl builder = createEditBuilder(offset, length);
+    try {
+      builder.write(text);
+    } finally {
+      fileEdit.add(builder.sourceEdit);
+    }
+  }
+
   EditBuilderImpl createEditBuilder(int offset, int length) {
     return new EditBuilderImpl(this, offset, length);
   }