Change Size::IsEmpty() to be consistent with Rect::IsEmpty()

base/gfx/rect.cc

Index: base/gfx/rect.cc
===================================================================
--- base/gfx/rect.cc	(revision 14559)
+++ base/gfx/rect.cc	(working copy)
@@ -90,19 +90,9 @@
 #endif
 
 void Rect::set_width(int width) {
-  if (width < 0) {
-    NOTREACHED();
-    width = 0;
-  }
-
   size_.set_width(width);
 }
 void Rect::set_height(int height) {
-  if (height < 0) {
-    NOTREACHED();
-    height = 0;
-  }
-
   size_.set_height(height);
 }
 
@@ -123,10 +113,6 @@
   set_y(y() + vertical);
 }
 
-bool Rect::IsEmpty() const {
-  return width() == 0 || height() == 0;
-}
-
 bool Rect::operator==(const Rect& other) const {
   return origin_ == other.origin_ && size_ == other.size_;
 }