fix bugs found by computing flat clips in 800K skps

src/pathops/SkPathOpsTypes.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.
  */
 #ifndef SkPathOpsTypes_DEFINED
 #define SkPathOpsTypes_DEFINED
 
 #include <float.h>  // for FLT_EPSILON
@@ skipping 73 matching lines @@
 const double FLT_EPSILON_HALF = FLT_EPSILON / 2;
 const double FLT_EPSILON_DOUBLE = FLT_EPSILON * 2;
 const double FLT_EPSILON_ORDERABLE_ERR = FLT_EPSILON * 16;
 const double FLT_EPSILON_SQUARED = FLT_EPSILON * FLT_EPSILON;
 const double FLT_EPSILON_SQRT = sqrt(FLT_EPSILON);
 const double FLT_EPSILON_INVERSE = 1 / FLT_EPSILON;
 const double DBL_EPSILON_ERR = DBL_EPSILON * 4;  // FIXME: tune -- allow a few bits of error
 const double DBL_EPSILON_SUBDIVIDE_ERR = DBL_EPSILON * 16;
 const double ROUGH_EPSILON = FLT_EPSILON * 64;
 const double MORE_ROUGH_EPSILON = FLT_EPSILON * 256;
+const double WAY_ROUGH_EPSILON = FLT_EPSILON * 2048;
+
+inline bool zero_or_one(double x) {
+    return x == 0 || x == 1;
+}
 
 inline bool approximately_zero(double x) {
     return fabs(x) < FLT_EPSILON;
 }
 
 inline bool precisely_zero(double x) {
     return fabs(x) < DBL_EPSILON_ERR;
 }
 
 inline bool precisely_subdivide_zero(double x) {
@@ skipping 186 matching lines @@
     return a <= c ? precisely_negative(a - b) && precisely_negative(b - c)
             : precisely_negative(b - a) && precisely_negative(c - b);
 }
 
 // returns true if (a <= b <= c) || (a >= b >= c)
 inline bool between(double a, double b, double c) {
     SkASSERT(((a <= b && b <= c) || (a >= b && b >= c)) == ((a - b) * (c - b) <= 0));
     return (a - b) * (c - b) <= 0;
 }
 
+inline bool roughly_equal(double x, double y) {
+    return fabs(x - y) < ROUGH_EPSILON;
+}
+
 inline bool more_roughly_equal(double x, double y) {
     return fabs(x - y) < MORE_ROUGH_EPSILON;
 }
 
-inline bool roughly_equal(double x, double y) {
-    return fabs(x - y) < ROUGH_EPSILON;
+inline bool way_roughly_equal(double x, double y) {
+    return fabs(x - y) < WAY_ROUGH_EPSILON;
 }
 
 struct SkDPoint;
 struct SkDVector;
 struct SkDLine;
 struct SkDQuad;
 struct SkDTriangle;
 struct SkDCubic;
 struct SkDRect;
 
@@ skipping 46 matching lines @@
 */
 inline int SkDSideBit(double x) {
     return 1 << SKDSide(x);
 }
 
 inline double SkPinT(double t) {
     return precisely_less_than_zero(t) ? 0 : precisely_greater_than_one(t) ? 1 : t;
 }
 
 #endif