fix minor skp-found bugs

src/pathops/SkDLineIntersection.cpp

 /*
  * 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 "SkIntersections.h"
 #include "SkPathOpsLine.h"
 
 /* Determine the intersection point of two lines. This assumes the lines are not parallel,
@@ skipping 274 matching lines @@
         fT[0][0] = vertical_intercept(line, x);
     } else if (verticalType == 2) {
         fT[0][0] = 0;
         fT[0][1] = 1;
     }
     return fUsed = verticalType;
 }
 
 int SkIntersections::vertical(const SkDLine& line, double top, double bottom,
                               double x, bool flipped) {
-    fMax = 2;
+    fMax = 3;  // cleanup parallel lines will bring this back line
     // see if end points intersect the opposite line
     double t;
     SkDPoint topPt = { x, top };
     if ((t = line.exactPoint(topPt)) >= 0) {
         insert(t, (double) flipped, topPt);
     }
     if (top != bottom) {
         SkDPoint bottomPt = { x, bottom };
         if ((t = line.exactPoint(bottomPt)) >= 0) {
             insert(t, (double) !flipped, bottomPt);
@@ skipping 31 matching lines @@
                 insert(t, (double) !flipped, bottomPt);
             }
             for (int index = 0; index < 2; ++index) {
                 if ((t = SkDLine::NearPointV(line[index], top, bottom, x)) >= 0) {
                     insert((double) index, flipped ? 1 - t : t, line[index]);
                 }
             }
         }
     }
     cleanUpParallelLines(result == 2);
+    SkASSERT(fUsed <= 2);
     return fUsed;
 }
 
 // from http://www.bryceboe.com/wordpress/wp-content/uploads/2006/10/intersect.py
 // 4 subs, 2 muls, 1 cmp
 static bool ccw(const SkDPoint& A, const SkDPoint& B, const SkDPoint& C) {
     return (C.fY - A.fY) * (B.fX - A.fX) > (B.fY - A.fY) * (C.fX - A.fX);
 }
 
 // 16 subs, 8 muls, 6 cmps
 bool SkIntersections::Test(const SkDLine& a, const SkDLine& b) {
     return ccw(a[0], b[0], b[1]) != ccw(a[1], b[0], b[1])
             && ccw(a[0], a[1], b[0]) != ccw(a[0], a[1], b[1]);
 }