fixes for conics

- use std tolerance in edgebuilder, since the path has not been scaled-up to its super-sample size (that happens in the builder methods.

- off-by-1 fix for pathops when using the output of the conicquadder

BUG=skia:

Review URL: https://codereview.chromium.org/837023002
diff --git a/src/pathops/SkOpEdgeBuilder.cpp b/src/pathops/SkOpEdgeBuilder.cpp
index 8503af3..803a5f4 100644
--- a/src/pathops/SkOpEdgeBuilder.cpp
+++ b/src/pathops/SkOpEdgeBuilder.cpp
@@ -111,8 +111,8 @@
                     for (int i = 0; i < nQuads; ++i) {
                        fPathVerbs.push_back(SkPath::kQuad_Verb);
                     }
-                    fPathPts.push_back_n(nQuads * 2, quadPts);
-                    curve[0] = quadPts[nQuads * 2 - 1];
+                    fPathPts.push_back_n(nQuads * 2, &quadPts[1]);
+                    curve[0] = pts[2];
                     lastCurve = true;
                 }
                 continue;