use inline version of eval quad if tangent is not needed

src/core/SkStroke.cpp

 /*
  * Copyright 2008 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 "SkStrokerPriv.h"
 #include "SkGeometry.h"
 #include "SkPath.h"
@@ skipping 658 matching lines @@
     (void) this->quadStroke(quad, &quadPts);
     this->setQuadEndNormal(quad, normalAB, unitAB, &normalBC, &unitBC);
 
     this->postJoinTo(pt2, normalBC, unitBC);
 }
 
 // Given a point on the curve and its derivative, scale the derivative by the radius, and
 // compute the perpendicular point and its tangent.
 void SkPathStroker::setRayPts(const SkPoint& tPt, SkVector* dxy, SkPoint* onPt,
         SkPoint* tangent) const {
+#if 01
     SkPoint oldDxy = *dxy;
     if (!dxy->setLength(fRadius)) {  // consider moving double logic into SkPoint::setLength
         double xx = oldDxy.fX;
         double yy = oldDxy.fY;
         double dscale = fRadius / sqrt(xx * xx + yy * yy);
         dxy->fX = SkDoubleToScalar(xx * dscale);
         dxy->fY = SkDoubleToScalar(yy * dscale);
     }
+#else
+    SkScalar scale = fRadius * sk_float_rsqrt(dxy->fX * dxy->fX + dxy->fY * dxy->fY);
+    dxy->fX *= scale;
+    dxy->fY *= scale;
+#endif
     SkScalar axisFlip = SkIntToScalar(fStrokeType);  // go opposite ways for outer, inner
     onPt->fX = tPt.fX + axisFlip * dxy->fY;
     onPt->fY = tPt.fY - axisFlip * dxy->fX;
     if (tangent) {
         tangent->fX = onPt->fX + dxy->fX;
         tangent->fY = onPt->fY + dxy->fY;
     }
 }
 
 // Given a conic and t, return the point on curve, its perpendicular, and the perpendicular tangent.
@@ skipping 753 matching lines @@
         default:
             break;
     }
 
     if (fWidth < SkMinScalar(rw, rh) && !fDoFill) {
         r = rect;
         r.inset(radius, radius);
         dst->addRect(r, reverse_direction(dir));
     }
 }