ui: Remove gfx::Size::ClampToNonNegative, prevent negative sizes always.

ui/gfx/rect_unittest.cc

Index: ui/gfx/rect_unittest.cc
diff --git a/ui/gfx/rect_unittest.cc b/ui/gfx/rect_unittest.cc
index f8222c6a5b007a73e1a8516c2cae18e143492da2..dce1e38284fcd99cae60b677a448d0825f331eda 100644
--- a/ui/gfx/rect_unittest.cc
+++ b/ui/gfx/rect_unittest.cc
@@ -433,10 +433,7 @@ TEST(RectTest, ScaleRect) {
       std::numeric_limits<float>::max(),
       std::numeric_limits<float>::max(),
       std::numeric_limits<float>::max(),
-      std::numeric_limits<float>::max() },
-    { 3, 3, 3, 3,
-      -1.0f,
-      -3.0f, -3.0f, 0.0f, 0.0f }
+      std::numeric_limits<float>::max() }
   };
 
   for (size_t i = 0; i < ARRAYSIZE_UNSAFE(tests); ++i) {