Use "int" rather than "long" for C++ code interacting with WebIDL's "long".

Source/modules/mediastream/RTCDTMFSender.h

Index: Source/modules/mediastream/RTCDTMFSender.h
diff --git a/Source/modules/mediastream/RTCDTMFSender.h b/Source/modules/mediastream/RTCDTMFSender.h
index b8fa66fd58f722ab395367b095a61217c44681dc..98f3299700cac19f5acc94dc72f75f6885466da6 100644
--- a/Source/modules/mediastream/RTCDTMFSender.h
+++ b/Source/modules/mediastream/RTCDTMFSender.h
@@ -53,12 +53,12 @@ public:
     bool canInsertDTMF() const;
     MediaStreamTrack* track() const;
     String toneBuffer() const;
-    long duration() const { return m_duration; }
-    long interToneGap() const { return m_interToneGap; }
+    int duration() const { return m_duration; }
+    int interToneGap() const { return m_interToneGap; }
 
     void insertDTMF(const String& tones, ExceptionState&);
-    void insertDTMF(const String& tones, long duration, ExceptionState&);
-    void insertDTMF(const String& tones, long duration, long interToneGap, ExceptionState&);
+    void insertDTMF(const String& tones, int duration, ExceptionState&);
+    void insertDTMF(const String& tones, int duration, int interToneGap, ExceptionState&);
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(tonechange);
 
@@ -81,8 +81,8 @@ private:
     virtual void didPlayTone(const WebString&) override;
 
     Member<MediaStreamTrack> m_track;
-    long m_duration;
-    long m_interToneGap;
+    int m_duration;
+    int m_interToneGap;
 
     OwnPtr<WebRTCDTMFSenderHandler> m_handler;