src: allow Blob reader setWakeup(undefined) to clear wakeup

Backport prerequisite for the previous commit (backport of #63577).

The Blob.stream() leak fix clears the reader's wakeup handle by calling
reader.setWakeup(undefined) on every terminal/idle path. On main the C++
Blob::Reader::SetWakeup already tolerates an undefined argument
(resetting the strong wakeup_ handle), but that guard is not present on
v24.x -- it landed incidentally in the large QUIC implementation commit
cf91d18 (#62876), which is not itself being backported.

Extract only the minimal node_blob.cc SetWakeup hunk from that commit so
the JS fix works on v24.x. Without it, setWakeup(undefined) aborts with
`Assertion failed: args[0]->IsFunction()` at src/node_blob.cc. The
NotifyPull(fin)/pull_pending_ coalescing from the same upstream commit
is QUIC-specific, not required by the leak fix, and is intentionally
omitted.

Refs: #63577
Refs: #62876
Signed-off-by: Gabe Bryk <gbryk11@gmail.com>

Author: gabrielbryk

src/node_blob.cc

@@ -414,6 +414,10 @@ void Blob::Reader::Pull(const FunctionCallbackInfo<Value>& args) {
 void Blob::Reader::SetWakeup(const FunctionCallbackInfo<Value>& args) {
   Blob::Reader* reader;
   ASSIGN_OR_RETURN_UNWRAP(&reader, args.This());
+  if (args[0]->IsUndefined()) {
+    reader->wakeup_.Reset();
+    return;
+  }
   CHECK(args[0]->IsFunction());
   reader->wakeup_.Reset(args.GetIsolate(), args[0].As<Function>());
 }