Remove damage argument in Toplevel::resetDamage

We always reset with the complete window geometry, so the subtracting
doesn't make any sense. We can just always set the damage to an empty
region.

REVIEW: 110438

composite.cpp

@@ -1026,12 +1026,9 @@ void Toplevel::addDamageFull()
     emit damaged(this, rect());
 }
 
-void Toplevel::resetDamage(const QRect& r)
+void Toplevel::resetDamage()
 {
-    damage_region -= r;
-    int damageArea = 0;
-    foreach (const QRect &r2, damage_region.rects())
-        damageArea += r2.width()*r2.height();
+    damage_region = QRegion();
 }
 
 void Toplevel::addRepaint(const QRect& r)

scene_opengl.cpp

@@ -921,7 +921,7 @@ bool SceneOpenGL::Window::bindTexture()
         if (!toplevel->damage().isEmpty()) {
             // mipmaps need to be updated
             texture->setDirty();
-            toplevel->resetDamage(QRect(toplevel->clientPos(), toplevel->clientSize()));
+            toplevel->resetDamage();
         }
         return true;
     }
@@ -934,7 +934,7 @@ bool SceneOpenGL::Window::bindTexture()
                                 toplevel->damage());
 
     if (success)
-        toplevel->resetDamage(QRect(toplevel->clientPos(), toplevel->clientSize()));
+        toplevel->resetDamage();
     else
         kDebug(1212) << "Failed to bind window";
     return success;

scene_xrender.cpp

@@ -329,7 +329,7 @@ xcb_render_picture_t SceneXrender::Window::picture()
             return XCB_RENDER_PICTURE_NONE;
         _picture = xcb_generate_id(connection());
         xcb_render_create_picture(connection(), _picture, pix, format, 0, NULL);
-        toplevel->resetDamage(toplevel->rect());
+        toplevel->resetDamage();
     }
     return _picture;
 }

toplevel.h

@@ -252,7 +252,7 @@ public:
     QRegion repaints() const;
     void resetRepaints();
     QRegion damage() const;
-    void resetDamage(const QRect& r);
+    void resetDamage();
     EffectWindowImpl* effectWindow();
     const EffectWindowImpl* effectWindow() const;
     /**