[Reland] Fix SkTwoPointConicalGradient zero-radius handling

src/effects/gradients/SkTwoPointConicalGradient.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTwoPointConicalGradient.h"
 #include "SkTwoPointConicalGradient_gpu.h"
 
@@ skipping 104 matching lines @@
     fB += fDB;
 
     if (0 == countRoots) {
         return TwoPtRadial::kDontDrawT;
     }
 
     // Prefer the bigger t value if both give a radius(t) > 0
     // find_quad_roots returns the values sorted, so we start with the last
     float t = roots[countRoots - 1];
     float r = lerp(fRec.fRadius, fRec.fDRadius, t);
-    if (r <= 0) {
+    if (r < 0) {
         t = roots[0];   // might be the same as roots[countRoots-1]
         r = lerp(fRec.fRadius, fRec.fDRadius, t);
-        if (r <= 0) {
+        if (r < 0) {
             return TwoPtRadial::kDontDrawT;
         }
     }
     return SkFloatToFixed(t);
 }
 
 typedef void (*TwoPointConicalProc)(TwoPtRadialContext* rec, SkPMColor* dstC,
                                     const SkPMColor* cache, int toggle, int count);
 
 static void twopoint_clamp(TwoPtRadialContext* rec, SkPMColor* SK_RESTRICT dstC,
@@ skipping 249 matching lines @@
     str->appendScalar(fCenter2.fY);
     str->append(") radius2: ");
     str->appendScalar(fRadius2);
     str->append(" ");
 
     this->INHERITED::toString(str);
 
     str->append(")");
 }
 #endif