remove prototype pathops code

experimental/Intersection/LineUtilities.h

-/*
- * Copyright 2012 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-#include "DataTypes.h"
-
-bool implicitLine(const _Line& line, double& slope, double& axisIntercept);
-int reduceOrder(const _Line& line, _Line& reduced);
-double is_left(const _Line& line, const _Point& pt);
-void sub_divide(const _Line& src, double t1, double t2, _Line& dst);
-double t_at(const _Line&, const _Point& );
-void xy_at_t(const _Line& , double t, double& x, double& y);
-_Point xy_at_t(const _Line& , double t);
-
-enum x_at_flags {
-    kFindTopMin = 1,
-    kFindTopMax = 2,
-    kFindBottomMin = 4,
-    kFindBottomMax = 8
-};
-
-void x_at(const _Point& p1, const _Point& p2, double minY, double maxY,
-        int flags, double& tMin, double& tMax);