Make SkMatrix::get*Scale[s]() fail on NaN

tests/MatrixTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkMath.h"
 #include "SkMatrix.h"
 #include "SkMatrixUtils.h"
@@ skipping 187 matching lines @@
     REPORTER_ASSERT(reporter, SK_Scalar1 == translate.getMinScale());
     REPORTER_ASSERT(reporter, SK_Scalar1 == translate.getMaxScale());
     success = translate.getMinMaxScales(scales);
     REPORTER_ASSERT(reporter, success && SK_Scalar1 == scales[0] && SK_Scalar1 == scales[1]);
 
     SkMatrix perspX;
     perspX.reset();
     perspX.setPerspX(SK_Scalar1 / 1000);
     REPORTER_ASSERT(reporter, -SK_Scalar1 == perspX.getMinScale());
     REPORTER_ASSERT(reporter, -SK_Scalar1 == perspX.getMaxScale());
-    // Verify that getMinMaxScales() doesn't update the scales array on failure.
-    scales[0] = -5;
-    scales[1] = -5;
     success = perspX.getMinMaxScales(scales);
-    REPORTER_ASSERT(reporter, !success && -5 * SK_Scalar1 == scales[0] && -5 * SK_Scalar1  == scales[1]);
+    REPORTER_ASSERT(reporter, !success);
+
+    // skbug.com/4718
+    SkMatrix big;
+    big.setAll(2.39394089e+36f, 8.85347779e+36f, 9.26526204e+36f,
+               3.9159619e+36f, 1.44823453e+37f, 1.51559342e+37f,
+               0.f, 0.f, 1.f);
+    REPORTER_ASSERT(reporter, -SK_Scalar1 == perspX.getMinScale());
+    REPORTER_ASSERT(reporter, -SK_Scalar1 == perspX.getMaxScale());
+    success = big.getMinMaxScales(scales);
+    REPORTER_ASSERT(reporter, !success);
 
     SkMatrix perspY;
     perspY.reset();
     perspY.setPerspY(-SK_Scalar1 / 500);
     REPORTER_ASSERT(reporter, -SK_Scalar1 == perspY.getMinScale());
     REPORTER_ASSERT(reporter, -SK_Scalar1 == perspY.getMaxScale());
     scales[0] = -5;
     scales[1] = -5;
     success = perspY.getMinMaxScales(scales);
     REPORTER_ASSERT(reporter, !success && -5 * SK_Scalar1 == scales[0] && -5 * SK_Scalar1  == scales[1]);
@@ skipping 716 matching lines @@
     a.setTranslate(10, 20);
 
     SkMatrix b;
     b.setScale(3, 5);
 
     SkMatrix expected;
     expected.setConcat(a,b);
 
     REPORTER_ASSERT(r, expected == SkMatrix::Concat(a, b));
 }