Adjust gfx::Rect's width and height to avoid integer overflow

ui/gfx/geometry/rect.cc

Index: ui/gfx/geometry/rect.cc
diff --git a/ui/gfx/geometry/rect.cc b/ui/gfx/geometry/rect.cc
index e7a3aa2aac93f14eb96c4832a130f4bbeafa9253..2a78d0b5c6e3696adeee8d5ffffa32b034e819f9 100644
--- a/ui/gfx/geometry/rect.cc
+++ b/ui/gfx/geometry/rect.cc
@@ -71,10 +71,16 @@ void Rect::Inset(int left, int top, int right, int bottom) {
 
 void Rect::Offset(int horizontal, int vertical) {
   origin_ += Vector2d(horizontal, vertical);
+  // Ensure that width and height remain valid.
+  set_width(width());
+  set_height(height());
 }
 
 void Rect::operator+=(const Vector2d& offset) {
   origin_ += offset;
+  // Ensure that width and height remain valid.
+  set_width(width());
+  set_height(height());
 }
 
 void Rect::operator-=(const Vector2d& offset) {