[test] Fix string length in generate-bytecode-expectations

Change-Id: Ieed04203b400f33dcb05eebd42b74db322c0c833
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1648097
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62023}

test/cctest/interpreter/generate-bytecode-expectations.cc

@@ -297,8 +297,8 @@ void ProgramOptions::UpdateFromHeader(std::istream& stream) {
       oneshot_opt_ = ParseBoolean(line.c_str() + strlen(kOneshotOpt));
     } else if (line.compare(0, 17, "async iteration: ") == 0) {
       async_iteration_ = ParseBoolean(line.c_str() + 17);
-    } else if (line.compare(0, 16, "private methods: ") == 0) {
-      private_methods_ = ParseBoolean(line.c_str() + 16);
+    } else if (line.compare(0, 17, "private methods: ") == 0) {
+      private_methods_ = ParseBoolean(line.c_str() + 17);
     } else if (line == "---") {
       break;
     } else if (line.empty()) {