[debug] Partial reland of debug API removal

src/debug/debug.h

Index: src/debug/debug.h
diff --git a/src/debug/debug.h b/src/debug/debug.h
index 8d2f8d5974d9db3e8f6d32c09dca7a72beb88c66..61cddaf6eeb3ab9118c53f32b3294c054be2645c 100644
--- a/src/debug/debug.h
+++ b/src/debug/debug.h
@@ -406,7 +406,6 @@ class Debug {
   void OnThrow(Handle<Object> exception);
   void OnPromiseReject(Handle<Object> promise, Handle<Object> value);
   void OnCompileError(Handle<Script> script);
-  void OnBeforeCompile(Handle<Script> script);
   void OnAfterCompile(Handle<Script> script);
   void OnAsyncTaskEvent(Handle<String> type, Handle<Object> id,
                         Handle<String> name);