Remove duplicate initialization of nsDeviceContext reference count by derived class constructor (which is dangerous since it could be incremented during the base class constructor). Various other cleanup, mostly in xlib port. b=111088 r=rbs sr=jag

widget/src/mac/nsDeviceContextMac.cpp

@@ -78,10 +78,10 @@ PRUint32 nsDeviceContextMac::sNumberOfScreens = 0;
  *	@update 12/9/98 dwc
  */
 nsDeviceContextMac :: nsDeviceContextMac()
-  : mSurface(nsnull), mOldPort(nsnull)
+  : DeviceContextImpl(),
+    mSurface(nsnull),
+    mOldPort(nsnull)
 {
-  NS_INIT_REFCNT();
-  
 }
 
 /** ---------------------------------------------------