Add better bounds checks for getTime to fix perf debug assert below

src/utils/SkCurveMeasure.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCurveMeasure_DEFINED
 #define SkCurveMeasure_DEFINED
 
@@ skipping 26 matching lines @@
     SkSegType fSegType;
 
     // precomputed coefficients for derivatives in Horner form
     Sk8f xCoeff[3];
     Sk8f yCoeff[3];
 };
 
 class SkCurveMeasure {
 public:
     SkCurveMeasure() {}
+
+    // Almost exactly the same as in SkPath::Iter:
+    // kLine_SegType  -> 2 points: start end
+    // kQuad_SegType  -> 3 points: start control end
+    // kCubic_SegType -> 4 points: start control1 control2 end
+    // kConic_SegType -> 4 points: start control end (w, w)
+    //
+    // i.e. the only difference is that the conic's last point is a point
+    // consisting of the w value twice
     SkCurveMeasure(const SkPoint* pts, SkSegType segType);
 
     SkScalar getTime(SkScalar targetLength);
     void getPosTanTime(SkScalar distance, SkPoint* pos, SkVector* tan, SkScalar* time);
     SkScalar getLength();
 
 private:
-    SkPoint evaluateQuad(SkScalar t);
-    SkVector evaluateQuadDerivative(SkScalar t);
-    //SkPoint evaluate_cubic(SkScalar t);
-    //SkVector evaluate_cubic_derivative(SkScalar t);
-    //SkPoint evaluate_conic(SkScalar t);
-    //SkVector evaluate_conic_derivative(SkScalar t);
-
     const SkScalar kTolerance = 0.0001f;
     const int kNewtonIters = 5;
     const int kBisectIters = 5;
 
     SkSegType fSegType;
     SkPoint fPts[4];
     SkScalar fLength = -1.0f;
     ArcLengthIntegrator fIntegrator;
 
     // for debug purposes
     int fIters;
 };
 
 #endif  // SkCurveMeasure_DEFINED