Bug 780489: Fix some compiler warnings in plugin and mac code. r=smichaud

dom/plugins/base/nsPluginHost.cpp

@@ -2201,7 +2201,7 @@ nsresult nsPluginHost::ScanPluginsDirectory(nsIFile *pluginsDir,
     // Avoid adding different versions of the same plugin if they are running 
     // in-process, otherwise we risk undefined behaviour.
     if (!nsNPAPIPlugin::RunPluginOOP(pluginTag)) {
-      if (nsPluginTag *duplicate = HaveSamePlugin(pluginTag)) {
+      if (HaveSamePlugin(pluginTag)) {
         continue;
       }
     }

dom/plugins/ipc/PluginInstanceParent.cpp

@@ -12,7 +12,6 @@
 #include "StreamNotifyParent.h"
 #include "npfunctions.h"
 #include "nsAutoPtr.h"
-#include "mozilla/unused.h"
 #include "gfxASurface.h"
 #include "gfxContext.h"
 #include "gfxPlatform.h"

dom/plugins/ipc/PluginInstanceParent.h

@@ -28,6 +28,7 @@
 class gfxXlibSurface;
 #endif
 #include "nsGUIEvent.h"
+#include "mozilla/unused.h"
 
 namespace mozilla {
 namespace plugins {
@@ -280,7 +281,7 @@ public:
     nsresult HandleGUIEvent(const nsGUIEvent& anEvent, bool* handled);
 #endif
 
-    void DidComposite() { SendNPP_DidComposite(); }
+    void DidComposite() { unused << SendNPP_DidComposite(); }
 
 private:
     // Create an appropriate platform surface for a background of size

widget/cocoa/nsFilePicker.mm

@@ -521,8 +521,7 @@ nsFilePicker::GetFilterList()
   NSMutableString* filterString = [[[NSMutableString alloc] initWithString:
                                     [NSString stringWithCharacters:filterWide.get()
 				              length:filterWide.Length()]] autorelease];
-  NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:
-                          [NSString stringWithString:@". *"]];
+  NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:@". *"];
   NSRange range = [filterString rangeOfCharacterFromSet:set];
   while (range.length) {
     [filterString replaceCharactersInRange:range withString:@""];