Bug 1615769 - Move using namespace mozilla in order to resolve conflicts with Windows headers. r=saschanaz

Differential Revision: https://phabricator.services.mozilla.com/D62989

--HG--
extra : moz-landing-system : lando

widget/windows/WindowsUIUtils.cpp

@@ -25,8 +25,6 @@
 #include "nsWindowGfx.h"
 #include "Units.h"
 
-using namespace mozilla;
-
 /* mingw currently doesn't support windows.ui.viewmanagement.h, so we disable it
  * until it's fixed. */
 #ifndef __MINGW32__
@@ -132,6 +130,8 @@ IDataPackage4 : public IInspectable {
 
 #endif
 
+using namespace mozilla;
+
 WindowsUIUtils::WindowsUIUtils() : mInTabletMode(eTabletModeUnknown) {}
 
 WindowsUIUtils::~WindowsUIUtils() {}