pathops work in progress

src/pathops/SkQuarticRoot.cpp

 // from http://tog.acm.org/resources/GraphicsGems/gems/Roots3And4.c
 /*
  *  Roots3And4.c
  *
  *  Utility functions to find cubic and quartic roots,
  *  coefficients are passed like this:
  *
  *      c[0] + c[1]*x + c[2]*x^2 + c[3]*x^3 + c[4]*x^4 = 0
  *
  *  The functions return the number of non-complex roots and
@@ skipping 53 matching lines @@
         int num = SkDCubic::RootsReal(t4, t3, t2, t1, roots);
         for (int i = 0; i < num; ++i) {
             if (approximately_zero(roots[i])) {
                 return num;
             }
         }
         roots[num++] = 0;
         return num;
     }
     if (oneHint) {
-        SkASSERT(approximately_zero(t4 + t3 + t2 + t1 + t0));  // 1 is one root
+        SkASSERT(approximately_zero_double(t4 + t3 + t2 + t1 + t0));  // 1 is one root
         // note that -C == A + B + D + E
         int num = SkDCubic::RootsReal(t4, t4 + t3, -(t1 + t0), -t0, roots);
         for (int i = 0; i < num; ++i) {
             if (approximately_equal(roots[i], 1)) {
                 return num;
             }
         }
         roots[num++] = 1;
         return num;
     }
@@ skipping 71 matching lines @@
                 if (j < --num) {
                     s[j] = s[num];
                 }
             } else {
                 ++j;
             }
         }
     }
     return num;
 }