fix bugs found by computing flat clips in 800K skps

src/pathops/SkPathOpsTypes.h

Index: src/pathops/SkPathOpsTypes.h
diff --git a/src/pathops/SkPathOpsTypes.h b/src/pathops/SkPathOpsTypes.h
index 4f8bd1534430ce8f3a7b0bca94dfdd1a967d00d1..96627842b3701a186792716bae400b6cfca0a639 100644
--- a/src/pathops/SkPathOpsTypes.h
+++ b/src/pathops/SkPathOpsTypes.h
@@ -91,6 +91,11 @@ const double DBL_EPSILON_ERR = DBL_EPSILON * 4;  // FIXME: tune -- allow a few b
 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;
@@ -297,12 +302,16 @@ inline bool between(double a, double b, double c) {
     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;