fixed a multiple definition of nsISupports. r=beard

gfx/src/mac/nsDeviceContextMac.cpp

@@ -67,12 +67,6 @@ nsDeviceContextMac :: ~nsDeviceContextMac()
 {
 }
 
-//------------------------------------------------------------------------
-
-NS_IMPL_QUERY_INTERFACE(nsDeviceContextMac, kDeviceContextIID);
-NS_IMPL_ADDREF(nsDeviceContextMac);
-NS_IMPL_RELEASE(nsDeviceContextMac);
-
 /** ---------------------------------------------------
  *  See documentation in nsIDeviceContext.h
  *	@update 12/9/98 dwc

gfx/src/mac/nsDeviceContextMac.h

@@ -37,8 +37,6 @@ class nsDeviceContextMac : public DeviceContextImpl
 public:
   nsDeviceContextMac();
 
-	NS_DECL_ISUPPORTS_INHERITED
-
   NS_IMETHOD  Init(nsNativeWidget aNativeWidget);  
 
   NS_IMETHOD  CreateRenderingContext(nsIRenderingContext *&aContext);