Optimize QuadF's PointIsInTriangle function

ui/gfx/geometry/quad_f.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_GEOMETRY_QUAD_F_H_
 #define UI_GFX_GEOMETRY_QUAD_F_H_
 
 #include <algorithm>
 #include <cmath>
 #include <string>
@@ skipping 34 matching lines @@
   const PointF& p4() const { return p4_; }
 
   // Returns true if the quad is an axis-aligned rectangle.
   bool IsRectilinear() const;
 
   // Returns true if the points of the quad are in counter-clockwise order. This
   // assumes that the quad is convex, and that no three points are collinear.
   bool IsCounterClockwise() const;
 
   // Returns true if the |point| is contained within the quad, or lies on on
-  // edge of the quad.
+  // edge of the quad. This assumes that the quad is convex.
   bool Contains(const gfx::PointF& point) const;
 
   // Returns a rectangle that bounds the four points of the quad. The points of
   // the quad may lie on the right/bottom edge of the resulting rectangle,
   // rather than being strictly inside it.
   RectF BoundingBox() const {
     float rl = std::min(std::min(p1_.x(), p2_.x()), std::min(p3_.x(), p4_.x()));
     float rr = std::max(std::max(p1_.x(), p2_.x()), std::max(p3_.x(), p4_.x()));
     float rt = std::min(std::min(p1_.y(), p2_.y()), std::min(p3_.y(), p4_.y()));
     float rb = std::max(std::max(p1_.y(), p2_.y()), std::max(p3_.y(), p4_.y()));
@@ skipping 34 matching lines @@
 
 // Add a vector to a quad, offseting each point in the quad by the vector.
 GFX_EXPORT QuadF operator+(const QuadF& lhs, const Vector2dF& rhs);
 // Subtract a vector from a quad, offseting each point in the quad by the
 // inverse of the vector.
 GFX_EXPORT QuadF operator-(const QuadF& lhs, const Vector2dF& rhs);
 
 }  // namespace gfx
 
 #endif  // UI_GFX_GEOMETRY_QUAD_F_H_