Avoid method call from ctor of SerialPort.

This CL is originally discussed on this CL below.
https://chromium-review.googlesource.com/c/chromium/src/+/2137200/3/third_party/blink/renderer/modules/webtransport/quic_transport.cc#248

Bug: 1049056
Change-Id: If7514d4237641e770adcceef5e857bc4681f1f94
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2141396Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Minoru Chikamune <chikamune@chromium.org>
Cr-Commit-Position: refs/heads/master@{#758476}

third_party/blink/renderer/modules/serial/serial_port.cc

@@ -161,8 +161,8 @@ class AbortCloseFunction : public ScriptFunction {
 SerialPort::SerialPort(Serial* parent, mojom::blink::SerialPortInfoPtr info)
     : info_(std::move(info)),
       parent_(parent),
-      port_(GetExecutionContext()),
-      client_receiver_(this, GetExecutionContext()) {}
+      port_(parent->GetExecutionContext()),
+      client_receiver_(this, parent->GetExecutionContext()) {}
 
 SerialPort::~SerialPort() = default;