fix arcto exception handling

src/core/SkPath.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBuffer.h"
 #include "SkCubicClipper.h"
 #include "SkErrorInternals.h"
@@ skipping 1253 matching lines @@
 // http://www.w3.org/TR/SVG/implnote.html#ArcConversionEndpointToCenter
 // Note that arcSweep bool value is flipped from the original implementation.
 void SkPath::arcTo(SkScalar rx, SkScalar ry, SkScalar angle, SkPath::ArcSize arcLarge,
                    SkPath::Direction arcSweep, SkScalar x, SkScalar y) {
     SkPoint srcPts[2];
     this->getLastPt(&srcPts[0]);
     // If rx = 0 or ry = 0 then this arc is treated as a straight line segment (a "lineto")
     // joining the endpoints.
     // http://www.w3.org/TR/SVG/implnote.html#ArcOutOfRangeParameters
     if (!rx || !ry) {
+        this->lineTo(x, y);
         return;
     }
     // If the current point and target point for the arc are identical, it should be treated as a
     // zero length path. This ensures continuity in animations.
     srcPts[1].set(x, y);
     if (srcPts[0] == srcPts[1]) {
+        this->lineTo(x, y);
         return;
     }
     rx = SkScalarAbs(rx);
     ry = SkScalarAbs(ry);
     SkVector midPointDistance = srcPts[0] - srcPts[1];
     midPointDistance *= 0.5f;
 
     SkMatrix pointTransform;
     pointTransform.setRotate(-angle);
 
@@ skipping 1913 matching lines @@
         }
     } while (!done);
     return SkToBool(tangents.count()) ^ isInverse;
 }
 
 int SkPath::ConvertConicToQuads(const SkPoint& p0, const SkPoint& p1, const SkPoint& p2,
                                 SkScalar w, SkPoint pts[], int pow2) {
     const SkConic conic(p0, p1, p2, w);
     return conic.chopIntoQuadsPOW2(pts, pow2);
 }