[debugger] track debugger feature usage via histogram.

src/runtime/runtime-liveedit.cc

Index: src/runtime/runtime-liveedit.cc
diff --git a/src/runtime/runtime-liveedit.cc b/src/runtime/runtime-liveedit.cc
index 947ef2c29b098207667d4db705624b1e60079459..5f2cac4938c0e0d2cb991b69729ef8f1217885ff 100644
--- a/src/runtime/runtime-liveedit.cc
+++ b/src/runtime/runtime-liveedit.cc
@@ -229,6 +229,8 @@ RUNTIME_FUNCTION(Runtime_LiveEditCompareStrings) {
   CONVERT_ARG_HANDLE_CHECKED(String, s1, 0);
   CONVERT_ARG_HANDLE_CHECKED(String, s2, 1);
 
+  isolate->debug()->feature_tracker()->Track(DebugFeatureTracker::kLiveEdit);
+
   return *LiveEdit::CompareStrings(s1, s2);
 }